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source/BYTE_AUG 83-A_New_Shape_Routine_for_the_Apple.txt
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A New Shape Subroutine for the Apple
|
||||
|
||||
by Richard T. Simoni Jr.
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August 1983 (c) BYTE Publications Inc
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Athletes pole-vault, race cars spin, and fighter planes
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fire at enemy aircraft. Is this the real world? No, I'm
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talking about fast, smooth animation on the Apple II
|
||||
high-resolution graphics screen. In the past year, dozens of
|
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new Apple II programs have achieved such awesome animation
|
||||
capabilities that several years ago most Apple programmers
|
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would scarcely have believed them possible. After trying
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unsuccessfully to match the quality of the commercially
|
||||
produced animation in my own assembly-language programs, I
|
||||
realized that the problem stemmed from the standard Apple
|
||||
shape subroutine that I was using to display the shapes I
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wanted to animate.
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Standard Hi-Res Package
|
||||
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The hi-res (high-resolution) graphics package I was
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||||
using is the standard package supplied by Apple Computer. It
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once was supplied with all Apple II computers sold, and it
|
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can now be found on the volume 3 disk of the Apple Software
|
||||
Bank Contributed Programs, available from Apple dealers.
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Indeed, this package was eventually incorporated into the
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Applesoft language to add hi-res commands. Written in
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machine language, the package includes subroutines to clear
|
||||
the screen, plot a point, draw a line, and draw a shape on
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the hi-res screen. Although the clear, plot, and line
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subroutines work well in animation, the shape subroutine is
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much too slow to allow shapes to move across the screen
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quickly, smoothly, and without flickering.
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The speed of the shape subroutine is the most important
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factor in animation for two main reasons. First, the speed
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with which the subroutine can plot the shape, erase it, and
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plot it again in its next position limits how fast any shape
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can move across the screen. Second, in a typical animation
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scheme, a shape moves from one position to the next in four
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phases, which correspond to the time required to plot the
|
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shape, the time the shape remains on the screen, the time
|
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required to erase the shape, and the time that the shape is
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not on the screen at all. These four phases repeat each time
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a shape moves to a new position. The time spent during each
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phase of the process determines how fast the shape moves and
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how smooth and flicker-free the animation looks. To maximize
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the smoothness, the time used in plotting the shape, erasing
|
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the shape, and leaving the shape off the screen must be
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minimized, for the human eye perceives these phases as
|
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contributing to the flicker of the image. On the other hand,
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if the amount of time the eye sees the image whole on the
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screen is significantly greater than the time required for
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the other phases, the image appears to move smoothly across
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the screen. Minimizing the time the image is totally off the
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screen is not difficult, for all calculations for the next
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plot can be done while the image is on the screen; when the
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image is erased, it can then be immediately plotted in the
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new position. The times required to plot and erase the
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shape, however, are directly determined by the speed of the
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image subroutine. If the subroutine is slow, the plot and
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erase times are long, and the image appears to flicker as it
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moves across the screen.
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Representing Shapes
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To understand why the standard Apple shape subroutine
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is too slow for most animation purposes, you must know how
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the subroutine works and especially how it expects a shape
|
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to be represented in memory. A shape is represented by a
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series of vectors in memory, with each vector specifying if
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a given pixel should be turned on. It also specifies which
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of the four adjacent pixels should be addressed by the next
|
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vector. This scheme best suits the representation of simple,
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single-line shapes such as those in figure 1. Unfortunately,
|
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if a shape must be filled in or if the shape has any detail
|
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drawn within its boundaries, as in figure 2, the shape's
|
||||
representation is awkward and inefficient at best. In these
|
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cases it is often necessary to overplot points and use many
|
||||
vectors that specify motion without plotting. Moreover, if
|
||||
the shape is large, the sheer size of the vector table
|
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becomes unwieldy. When the time comes to plot these shapes,
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the subroutine steps through the table, and each vector
|
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takes up a certain amount of time. If the vector table
|
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represents the shape inefficiently, the end result is wasted
|
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time in the plotting of the shape.
|
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Similarly contributing to the slow speed of the shape
|
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subroutine is the inclusion of scaling and rotation factors.
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In order to plot a shape, a calling routine must specify a
|
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scaling factor that determines the plotted shape's size
|
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(actual size, double size, triple size, etc.) and a rotation
|
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factor that determines the angle through which the shape is
|
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rotated before plotting. Although these factors are useful
|
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in some applications, using them with shape animation rarely
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produces satisfying results, and these calculations slow the
|
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subroutine considerably.
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A New Shape Subroutine
|
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After realizing that the speed bottleneck in my
|
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programs was caused by the shape subroutine, I went about
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designing my own subroutine with two criteria in mind.
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First, the subroutine had to be high speed to minimize image
|
||||
flicker, and second, the method of representing a shape in
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memory had to allow complicated images to be plotted as
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||||
quickly as simple single-line shapes of the same overall
|
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size. One way to meet these criteria is to use a bit picture
|
||||
to represent the shape in memory. In other words, the shape
|
||||
is represented in main memory in the same form in which it
|
||||
is ultimately represented in the hi-res screen memory when
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the shape is plotted on the hi-res screen. Plotting the
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shape is then simple and fast: the bytes representing the
|
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shape in main memory need only be transferred to the hi-res
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||||
screen memory. I used this technique in writing a fast shape
|
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subroutine suitable for animation.
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The table of bytes that make up the bit picture is
|
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called the shape table. A shape table is most easily formed
|
||||
through the use of the shape-editor program presented later
|
||||
in this article. To form a shape table manually, start by
|
||||
drawing the shape on a piece of graph paper with one pixel
|
||||
per square, as in figure 3a. Use 1s to represent on pixels
|
||||
and 0s to represent off pixels. Draw the smallest possible
|
||||
rectangle that still encloses the entire figure. Then split
|
||||
each line of binary digits enclosed by the rectangle into
|
||||
7-bit groups. If, as in figure 3b, the last group doesn't
|
||||
have afull 7 bits, add enough 0s to the end of each line to
|
||||
bring the total up to 7 bits. Due to limitations to the
|
||||
subroutine, no more than seven 7-bit groups per line are
|
||||
allowed. Reverse the order of the bits in each group, as
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||||
shown in figure 3c. Convert each new 7-bit group into its
|
||||
hexadecimal or decimal equivalent, whichever is preferred
|
||||
(figure 3d shows the hexadecimal equivalent) and, reading
|
||||
across each line left to rightfrom the top to the bottom
|
||||
line, recopythe list of numbers in table (linear) form. The
|
||||
table is now complete except for two bytes that belong at
|
||||
the top of the table. The first of these butes represents
|
||||
the height of the shaps -- in other words, the number of
|
||||
lines of digits in figure 3b; the second byte represents the
|
||||
width of the shape in 7-bit groups that is, the number of
|
||||
7-bit groups used in each line in figure 3b. As previously
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||||
mentioned, this width should be no more than seven groups.
|
||||
The complete table in hexadecimal form for the sample shape
|
||||
used in figure 3 is as follows:
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||||
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||||
05 02 78 07 14 04 12 02
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||||
11 01 7F 00
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||||
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||||
The shape subroutine itself is shown in listing 1, and
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||||
the lookup tables used by the subroutine are shown in
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||||
listing 2. Before calling the subroutine, several registers
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||||
and memory locations must be set up with certain parameters,
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including the hi-res screen coordinates of the pixel where
|
||||
the upper left corner of the bit picture should be
|
||||
positioned. The low-order byte of the xcoordinate should be
|
||||
placed in theX register, and the corresponding highorder
|
||||
byte of the x coordinate (either 1 or 0) goes in the Y
|
||||
register. The ycoordinate goes in the A
|
||||
register(accumulator). The low- and high-order bytes of the
|
||||
shape-table starting address should be stored in hexadecimal
|
||||
memory locations EB and EC, respectively. The subroutine can
|
||||
then be called with the usual JSR instruction. A summary of
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||||
the parameter setup is given in table 1.
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||||
|
||||
The subroutine works by taking the exclusive-OR of each
|
||||
affected bit in page-1 hi-res screen memory with the
|
||||
corresponding bit of the bit picture. This exclusive-OR
|
||||
plotting has several advantages. First, a color need not be
|
||||
specified; the shape is drawn by calling the subroutine once
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||||
and is erased by simply calling it again with the same
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||||
screen coordinates. Second, any shape drawn using
|
||||
exclusive-OR plotting is nondestructive; that is, whatever
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the shape happens to plot over is restored when the shape is
|
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erased. This property can be used to form interesting
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backgrounds that need not be redrawn after shapes are
|
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plotted and moved on top of them. Cross-hair cursors are
|
||||
also free to move around without destroying the screen's
|
||||
previous contents.
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||||
|
||||
Several details about the subroutine need to be
|
||||
explained. Zero page (hexadecimal locations 00 through FF)
|
||||
of memory is used for temporary storage; the particular
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||||
locations used were chosen to avoid destruction of locations
|
||||
used by the Apple Monitor, Applesoft, Integer Basic, and the
|
||||
DOS (disk operating system). The subroutine does not operate
|
||||
correctly without the tables shown in listing 2. These
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||||
tables may be stored anywhere in memory, but are best
|
||||
located immediately after the subroutine in memory. Three
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||||
pertinent Text continued from page 303: tables are named
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||||
QUOTBL, LOSTRT, and HISTRT. QUOTBL is a lookup table used
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internally by the subroutine to divide the x-coordinate by
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||||
7. LOSTRT and HISTRT are each 192 bytes long, and they
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||||
contain the low- and high-order bytes of the address of the
|
||||
leftmost byte of each y-coordmate in page 1 of hi-res screen
|
||||
memory. For plotting on page 2 of the hi-res memory, a
|
||||
hexadecimal 20 should be added to each byte in the table
|
||||
HISTRT Although I wanted the subroutine to be fully
|
||||
relocatable, I compromised this requirement in favor of
|
||||
additional speed. However, as I have written it, relocating
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||||
the subroutine requires changing only the two locations
|
||||
referencing QUOTBL in lines 38 and 41 of listing 1.
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||||
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||||
A Note on Color
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||||
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||||
One of the most difficult aspects of using the Apple
|
||||
high-resolution graphics mode is trying to control the color
|
||||
of objects displayed on the screen. This difficulty arises
|
||||
because a color cannot be individually assigned to each
|
||||
pixel on the screen; the color depends instead on such
|
||||
factors as whether an object is drawn with pixels
|
||||
horizontally alternating between on and off and whether the
|
||||
on pixels have even or odd x coordinates. Through careful
|
||||
programming and shape-table composition, you can control
|
||||
colors in this manner using the shape subroutine presented
|
||||
in this article. In newer Apples, however, two more colors
|
||||
are added to the hi-res screen by defin-. ing the previously
|
||||
unused high-order bit in each word in hi-res screen memory.
|
||||
Unfortunately, these colors cannot be easily displayed using
|
||||
the shape subroutine because the subroutine forces the extra
|
||||
bit in the hi-res screen to 0. For a complete description of
|
||||
color in the Apple hi-res screen, see page 19 of the Apple
|
||||
II Reference Manual (Cupertino: Apple Computer Inc., 1979).
|
||||
|
||||
The Shape-Editor Program
|
||||
|
||||
Although it is not difficult to form the shape table
|
||||
for a given shape, it is often time consuming. When writing
|
||||
a program that uses shapes, you rarely know in advance the
|
||||
exact pixel pattern that makes up the shape. Even if you
|
||||
know the pattern, you're probably not sure whether the shape
|
||||
will look good on the hi-res screen. It might take you hours
|
||||
to develop a suitable shape if you have to write out each
|
||||
trial on graph paper, form the shape table, and use the
|
||||
subroutine to display the shape before you can tell if it is
|
||||
satisfactory. This time-consuming method can bring the
|
||||
creative process to a halt. A more desirable situation would
|
||||
be one in which you could easily experiment with different
|
||||
shapes on the hi-res screen until you were satisfied with
|
||||
the results and then form the shape table directly from the
|
||||
screen image. I had this concept in mind when writing the
|
||||
shape-editor program shown in listing 3. The program
|
||||
features complete hi-res editing, both actual size and a
|
||||
blown-up view of the shape being drawn, disk storage of the
|
||||
current shape (the source file) for future editing, and
|
||||
assembly of a shape table from any portion of the current
|
||||
screen.
|
||||
|
||||
The editor program requires an Apple II with 32K bytes
|
||||
of memory, a disk drive, and Applesoft in ROM (read-only
|
||||
memory). When you run the program, the list of commands
|
||||
shown in photo 1 comes up on the screen. After you press the
|
||||
space bar, the left area of the screen becomes blank, and a
|
||||
grid appears on the right. The blank area is the "slate" on
|
||||
which you can draw different shapes actual size. Anything
|
||||
drawn also appears enlarged on the grid, making it easier to
|
||||
see details of the shape. Once the grid has been drawn, a
|
||||
small horizontal line appears in one of the small squares in
|
||||
the grid. This is the cursor, which always shows the current
|
||||
drawing position of the program.
|
||||
|
||||
Once the cursor appears on the screen, you can execute
|
||||
any of the commands listed in the menu (photo 1) by pressing
|
||||
the corresponding letter on the keyboard. The letters I, J,
|
||||
K, and M are used for moving the graphics cursor up, left,
|
||||
right, and down, respectively. The Plot command plots a
|
||||
point at the current cursor position, and the Erase command
|
||||
erases the point at the current cursor position. Neither the
|
||||
Plot nor the Erase command causes any harm if the command
|
||||
has already been used at the cursor position (e.g., if the
|
||||
Plot command is used at a position where a point already
|
||||
exists). The Clear command clears the screen after prompting
|
||||
you to verify that the screen should indeed be cleared. By
|
||||
using the cursor-movement, Plot, Erase, and Clear commands,
|
||||
you can draw the desired shape on the screen and modify it
|
||||
as many times as necessary. A shape being drawn in this
|
||||
screen-edit mode is shown in photo 2.
|
||||
|
||||
With the Table command, you can make a shape table from
|
||||
any segment of the screen where you have drawn a shape.
|
||||
After choosing the Table command by pressing the T key, you
|
||||
must choose the smallest rectangle that encloses the shape;
|
||||
this is the same rectangle chosen when forming the shape
|
||||
table manually as previously described. You specify the
|
||||
boundaries of this rectangle by moving the cursor to the
|
||||
upper left position of the rectangle and pressing the Return
|
||||
key and then doing the same for the lower right corner of
|
||||
the rectangle. The corners are inclusive; that is, the rows
|
||||
and columns that contain the corners become the outermost
|
||||
edges included in the shape table. A portion of the
|
||||
rectangle selection process is shown in photo 3. After you
|
||||
select the desired rectangle, the program will form the
|
||||
shape table. The time this takes (typically 15 to 30
|
||||
seconds) depends on the size of the shape. The completed
|
||||
shape table is displayed on the screen in either decimal or
|
||||
hexadecimal form, depending on how you answer a prompt. The
|
||||
program will then save this object-file shape table on disk
|
||||
as a standard binary file if you so desire. You are then
|
||||
asked whether to return to the screen-edit mode or end the
|
||||
program. Photo 4 shows the final shape table formed from the
|
||||
sample shape used in photo 3.
|
||||
|
||||
The Save and Get commands let you store on disk and
|
||||
later retrieve any picture drawn in the screen-edit mode.
|
||||
The Save command prompts you for a file name and then saves
|
||||
to disk a representation of the shape drawn on the grid. The
|
||||
Get command can then be used to retrieve and display the
|
||||
picture as long as the saved file remains on disk. Because
|
||||
the Get command erases any drawing previously on the screen,
|
||||
you are first asked to confirm that a file is to be loaded.
|
||||
Once the picture is retrieved, it can be modified or
|
||||
assembled into a shape table just as if the picture had been
|
||||
entered using the keyboard commands.
|
||||
|
||||
The Help command (executed by pressing the H or ? key)
|
||||
returns you from the screen-edit mode to the menu shown at
|
||||
the beginning of the program for a quick command-letter
|
||||
check. Pressing the space bar returns you to screen-edit
|
||||
mode with the contents of the screen unaltered. The Quit
|
||||
command ends the program. Because any drawing on the screen
|
||||
is lost once the program is ended, you are asked to confirm
|
||||
the Quit directive.
|
||||
|
||||
Summing Up
|
||||
|
||||
Using the techniques and programs described in this
|
||||
article, you can implement professional-looking animation on
|
||||
the Apple without having to work around the limitations of
|
||||
the standard Apple shape subroutine. Although I wrote my
|
||||
shape subroutine with animation in mind, the subroutine is
|
||||
useful in any graphics applications where detailed shapes
|
||||
must be drawn. Using the graphics editor as a development
|
||||
tool, virtually any shape can be easily displayed on the
|
||||
hi-res screen.
|
||||
|
||||
|
||||
Richard T Simoni Jr. (29 Farnham Park Dr., Houston, TX
|
||||
77024) is currently enrolled as a senior electrical
|
||||
engineering/computer science/math science major at Rice
|
||||
University in Houston, Texas.
|
||||
|
||||
|
||||
|
||||
Figure 1: Because they are easily represented in memory by a
|
||||
series of vectors, these simple single-line closed shapes
|
||||
are suitable for display by the standard Apple shape
|
||||
subroutine on the hi-res graphics screen.
|
||||
|
||||
(1a) (1b) (1c)
|
||||
........... ........... ...............
|
||||
........... ........... ....*******....
|
||||
..*******.. ..*........ ...*.......*...
|
||||
..*.....*.. ..**....... ..*.........*..
|
||||
..*.....*.. ..*.*...... .*...........*.
|
||||
..*.....*.. ..*..*..... .*...........*.
|
||||
..*.....*.. ..*...*.... .*...........*.
|
||||
..*******.. ..*....*... .*...........*.
|
||||
........... ..*******.. .*...........*.
|
||||
........... ........... .*...........*.
|
||||
........... .*...........*.
|
||||
.*************.
|
||||
...............
|
||||
|
||||
|
||||
|
||||
Figure 2: The detail within these shapes makes their
|
||||
representation as vectors in memory inefficient; therefore,
|
||||
the standard Apple shape subroutine is neither well suited
|
||||
nor easy to use for the display of these shapes on the
|
||||
hi-res screen.
|
||||
|
||||
(2a) (2b) (2c)
|
||||
........... ..................... ...............
|
||||
........... .***************..... ....*******....
|
||||
..*******.. .*............*.*.... ...*.......*...
|
||||
..*******.. .*............*..*... ..*.........*..
|
||||
..*******.. .*............*...*.. .*...........*.
|
||||
..*******.. .*............******. .*************.
|
||||
..*******.. .*.................*. .*...........*.
|
||||
..*******.. .*******************. .*...........*.
|
||||
........... ..*****.......*****.. .*....***....*.
|
||||
........... ...***.........***... .*....*.*....*.
|
||||
..................... .*....*.*....*.
|
||||
.*************.
|
||||
...............
|
||||
|
||||
|
||||
|
||||
Figure 3: To form a shape table, start by drawing the
|
||||
desired shape on graph paper, using 1s and 0s to represent
|
||||
"on" and "off" pixels (3a). Next, split each line of bits
|
||||
into 7-bit groups, padding the last group of each line with
|
||||
0s if necessary (3b). Then, reverse the order of the binary
|
||||
digits in each 7-bit group (3c) and convert to hexadecimal
|
||||
(3d). Later you must add height and width bytes as described
|
||||
in the text.
|
||||
|
||||
(3a) (3b) (3c)
|
||||
............ split|here 1111000 0000111
|
||||
............ v 0010100 0000100
|
||||
....*******. 000000000000 0010010 0000010
|
||||
...*.*....*. 000000000000 0010001 0000001
|
||||
..*..*...*.. 000011111110 1111111 0000000
|
||||
.*...*..*... 000101000010
|
||||
.*******.... 001001000100
|
||||
............ 010001001000
|
||||
............ 011111110000
|
||||
000000000000
|
||||
000000000000 (3d)
|
||||
| |\ | 78 07
|
||||
0001111 1110000 14 04
|
||||
0010100 0010000 12 02
|
||||
0100100 0100000 11 01
|
||||
1000100 1000000 7F 00
|
||||
1111111 0000000
|
||||
| |
|
||||
added
|
||||
zeros
|
||||
|
||||
|
||||
|
||||
Listing 1: A fast shape subroutine that plots
|
||||
high-resolution shapes on the Apple II.
|
||||
|
||||
0000: 1 OBJ $1B00
|
||||
1B00: 2 ORG $1B00 ;ASSEMBLY LOCATION
|
||||
1B00: 3 *********************************************************
|
||||
1B00: 4 * SHAPE SUBROUTINE WRITTEN BY RICHARD T. SIMONI, JR. *
|
||||
1B00: 5 * *
|
||||
1B00: 6 * SHAPE WORKS BY STEPPING THROUGH THE USER TABLE ONE *
|
||||
1B00: 7 * HI-RES LINE AT A TIME, SHIFTING THE BIT PATTERN THE *
|
||||
1B00: 8 * APPROPRIATE NUMBER OF TIMES (DEPENDING ON THE *
|
||||
1B00: 9 * X-COORDINATE PASSED IN THE X- AND Y-REGISTERS), AND *
|
||||
1B00: 10 * MOVING THE PATTERN TO THE PROPER PLACE IN THE HI-RES *
|
||||
1B00: 11 * SCREEN MEMORY. *
|
||||
1B00: 12 *********************************************************
|
||||
1B00: 13 STARTZ EQU $19 ;START OF LINE STORAGE
|
||||
1B00: 14 YCOORD EQU $E3 ;LINE COUNTER
|
||||
1B00: 15 START EQU $EB ;USER TABLE POINTER
|
||||
1B00: 16 ADDRL EQU $ED ;1ST SCREEN BYTE TO USE
|
||||
1B00: 17 ADDRH EQU $EE ; IN LINE COORD
|
||||
1B00: 18 ADDRADD EQU $EF ;OFFSET FROM LEFT BYTE
|
||||
1B00: 19 SHFTNUM EQU $F9 ;NUMBER OF SHIFTS
|
||||
1B00: 20 ENDLN EQU $FD ;LAST LINE + 1
|
||||
1B00: 21 WIDTH EQU $FB ;WIDTH OF USER TABLE
|
||||
1B00: 22 INDEX EQU $FC ;POINTER IN USER TABLE
|
||||
1B00: 23 *
|
||||
1B00: 24 * DIVIDE X-COORD BY 7 TO GET BYTE OFFSET FROM LEFTMOST
|
||||
1B00: 25 * BYTE IN ANY HI-RES LINE. REMAINDER WILL BE CORRECT
|
||||
1B00: 26 * NUMBER OF SHIFTS TO PERFORM ON BIT PATTERN.
|
||||
1B00: 27 * DIVISION IS PERFORMED USING LOOKUP TABLE FOR SPEED.
|
||||
1B00: 28 *
|
||||
1B00: 85 E3 29 STA YCOORD ;STORE Y-COORD (COUNTER)
|
||||
1B02: 8A 30 TXA
|
||||
1B03: 0A 31 ASL A
|
||||
1B04: AA 32 TAX
|
||||
1B05: 98 33 TYA
|
||||
1B06: 2A 34 ROL A
|
||||
1B07: A8 35 TAY ;MULTIPLY X-COORD BY TWO
|
||||
1B08: 18 36 CLC
|
||||
1B09: 8A 37 TXA ;A-REG = X-COORD*2 LO-BYTE
|
||||
1B0A: 69 83 38 ADC #>QUOTBL ;ADD TABLE ADDRESS LO-BYTE
|
||||
1B0C: 85 ED 39 STA ADDRL ;STORE RESULT
|
||||
1B0E: 98 40 TYA ;A-REG = X-COORD*2 HI-BYTE
|
||||
1B0F: 69 18 41 ADC #<QUOTBL ;ADD TABLE ADDRESS HI-BYTE
|
||||
1B11: 85 EE 42 STA ADDRH ;STORE RESULT
|
||||
1B13: A0 00 43 LDY #$00 ;ZERO Y-REG FOR INDEXING
|
||||
1B15: B1 ED 44 LDA (ADDRL),Y ;LOAD X-COORD/7 FROM TABLE
|
||||
1B17: 85 EF 45 STA ADDRADD ;ADDRADD = XCOORD/7
|
||||
1B19: C8 46 INY ;REMAINDER FOLLOWS IN TABLE
|
||||
1B1A: B1 ED 47 LDA (ADDRL),Y ;LOAD REMAINDER FROM TABLE
|
||||
1B1C: 85 F9 48 STA SHFTNUM ;SHFTNUM = REMAINDER
|
||||
1B1E: 49 *
|
||||
1B1E: 50 * INITIALIZE LOCATIONS ENDLN AND WIDTH. ENDLN CONTAINS
|
||||
1B1E: 51 * THE Y-COORD OF THE LAST LINE + 1. WIDTH CONTAINS THE
|
||||
1B1E: 52 * WIDTH (IN BYTES) OF EACH LINE.
|
||||
1B1E: 53 *
|
||||
1B1E: A5 E3 54 LDA YCOORD
|
||||
1B20: A0 00 55 LDY #$00
|
||||
1B22: 18 56 CLC
|
||||
1B23: 71 EB 57 ADC (START),Y
|
||||
1B25: 85 FD 58 STA ENDLN ;ENDLN = Y-COORD+LENGTH
|
||||
1B27: C8 59 INY
|
||||
1B28: B1 EB 60 LDA (START),Y
|
||||
1B2A: 85 FB 61 STA WIDTH ;GET & STORE WIDTH
|
||||
1B2C: C8 62 INY
|
||||
1B2D: 84 FC 63 STY INDEX ;INDEX=2
|
||||
1B2F: 64 *
|
||||
1B2F: 65 * LOOP1 IS THE LOOP THAT IS CYCLED THROUGH ONCE FOR EACH
|
||||
1B2F: 66 * LINE ON THE HI-RES SCREEN
|
||||
1B2F: 67 *
|
||||
1B2F: A6 FB 68 LOOP1 LDX WIDTH ;X-REG=0 (COUNTER)
|
||||
1B31: A4 FC 69 LDY INDEX
|
||||
1B33: 70 *
|
||||
1B33: 71 * MOVE BYTES FOR LINE YCOORD FROM USER TABLE TO ZERO PAGE
|
||||
1B33: 72 *
|
||||
1B33: B1 EB 73 LOOP2 LDA (START),Y ;GET XTH BYTE OF LINE
|
||||
1B35: 95 19 74 STA STARTZ,X ;STORE IN STARTZ+X
|
||||
1B37: C8 75 INY
|
||||
1B38: CA 76 DEX ;MOVED ALL BYTES YET?
|
||||
1B39: D0 F8 77 BNE LOOP2 ;NO, LOOP
|
||||
1B3B: 86 19 78 STX STARTZ ;STARTZ=0
|
||||
1B3D: 84 FC 79 STY INDEX
|
||||
1B3F: 80 *
|
||||
1B3F: 81 * SHIFT THE BIT PATTERN SHIFTNUM TIMES
|
||||
1B3F: 82 *
|
||||
1B3F: A4 F9 83 LDY SHFTNUM ;IS SHFTNUM=0?
|
||||
1B41: F0 16 84 BEQ SKIP ;YES, SKIP THE SHIFTING
|
||||
1B43: 18 85 LOOP3 CLC ;NO, START SHIFTING
|
||||
1B44: A6 FB 86 LDX WIDTH
|
||||
1B46: 08 87 PHP ;KEEP STACK IN ORDER
|
||||
1B47: 28 88 LOOP4 PLP ;RESTORE CARRY
|
||||
1B48: B5 19 89 LDA STARTZ,X ;LOAD ORIGINAL PATTERN
|
||||
1B4A: 2A 90 ROL A
|
||||
1B4B: 2A 91 ROL A ;ROTATE LEFT TWICE
|
||||
1B4C: 08 92 PHP ;SAVE CARRY
|
||||
1B4D: 4A 93 LSR A ;SHIFT RIGHT ONCE
|
||||
1B4E: 95 19 94 STA STARTZ,X ;STORE SHIFTED PATTERN
|
||||
1B50: CA 95 DEX
|
||||
1B51: E0 FF 96 CPX #$FF ;ROTATED EACH BYTE?
|
||||
1B53: D0 F2 97 BNE LOOP4 ;NO, LOOP
|
||||
1B55: 28 98 PLP ;KEEP STACK IN ORDER
|
||||
1B56: 88 99 DEY
|
||||
1B57: D0 EA 100 BNE LOOP3 ;LOOP IF Y<>0
|
||||
1B59: 101 *
|
||||
1B59: 102 * CALCULATE HI-RES SCREEN ADDRESS FOR FIRST BYTE TO
|
||||
1B59: 103 * BE USED IN LINE YCOORD
|
||||
1B59: 104 *
|
||||
1B59: A4 E3 105 LDY YCOORD
|
||||
1B5B: B9 B3 1D 106 LDA LOSTRT,Y
|
||||
1B5E: 18 107 CLC
|
||||
1B5F: 65 EF 108 ADC ADDRADD
|
||||
1B61: 85 ED 109 STA ADDRL
|
||||
1B63: B9 73 1E 110 LDA HISTRT,Y
|
||||
1B66: 69 00 111 ADC #$00
|
||||
1B68: 85 EE 112 STA ADDRH ;GET ADDR FOR 1ST BYTE
|
||||
1B6A: 113 *
|
||||
1B6A: 114 * MOVE SHIFTED BYTES FROM ZERO PAGE TO HI-RES SCREEN
|
||||
1B6A: 115 * MEMORY. FOR NON-EXCLUSIVE-OR PLOTTING, CHANGE
|
||||
1B6A: 116 * 'EOR (ADDRL),Y' TO 'ORA (ADDRL),Y' (OPCODE $11).
|
||||
1B6A: 117 *
|
||||
1B6A: A0 00 118 LDY #$00
|
||||
1B6C: A6 FB 119 LDX WIDTH
|
||||
1B6E: B5 19 120 LOOP5 LDA STARTZ,X
|
||||
1B70: F1 ED 121 SBC (ADDRL),Y
|
||||
1B72: 91 ED 122 STA (ADDRL),Y ;PLOT BYTE ON SCREEN
|
||||
1B74: C8 123 INY
|
||||
1B75: CA 124 DEX
|
||||
1B76: E0 FF 125 CPX #$FF ;THROUGH PLOTTING LINE?
|
||||
1B78: D0 F4 126 BNE LOOP5 ;NO, LOOP
|
||||
1B7A: E6 E3 127 INC YCOORD ;YES, GO TO NEXT LINE
|
||||
1B7C: A5 E3 128 LDA YCOORD
|
||||
1B7E: C5 FD 129 CMP ENDLN ;MORE LINES?
|
||||
1B80: D0 AD 120 BNE $1B2F ;YES, LOOP
|
||||
1B82: 60 131 RTS ;NO, RETURN
|
||||
1B83: 132 QUOTBL EQU *
|
||||
1B83: 133 LOSTRT EQU *+560
|
||||
1B83: 134 HISTRT EQU *+752
|
||||
|
||||
*** SUCCESSFUL ASSEMBLY: NO ERRORS
|
||||
|
||||
|
||||
|
||||
Listing 2: Lookup tables used by the listing 1 subroutine.
|
||||
|
||||
1b83: 00 00 00 01 00 02 00 03 00 04 00 05 00
|
||||
1b90: 06 01 00 01 01 01 02 01 03 01 04 01 05 01 06 02
|
||||
1ba0: 00 02 01 02 02 02 03 02 04 02 05 02 06 03 00 03
|
||||
1bb0: 01 03 02 03 03 03 04 03 05 03 06 04 00 04 01 04
|
||||
1bc0: 02 04 03 04 04 04 05 04 06 05 00 05 01 05 02 05
|
||||
1bd0: 03 05 04 05 05 05 06 06 00 06 01 06 02 06 03 06
|
||||
1be0: 04 06 05 06 06 07 00 07 01 07 02 07 03 07 04 07
|
||||
1bf0: 05 07 06 08 00 08 01 08 02 08 03 08 04 08 05 08
|
||||
|
||||
1c00: 06 09 00 09 01 09 02 09 03 09 04 09 05 09 06 0a
|
||||
1c10: 00 0a 01 0a 02 0a 03 0a 04 0a 05 0a 06 0b 00 0b
|
||||
1c20: 01 09 02 0b 03 0b 04 0b 05 0b 06 0c 00 0c 01 0c
|
||||
1c30: 02 0c 03 0c 04 0c 05 0c 06 0d 00 00 01 00 02 00
|
||||
1c40: 03 00 04 00 05 00 06 08 00 0e 01 0e 02 0e 03 0e
|
||||
1c50: 04 0e 05 0e 06 0f 00 0f 01 0f 02 0f 03 0f 04 0f
|
||||
1c60: 05 0f 06 10 00 10 01 10 02 10 03 10 04 10 05 10
|
||||
1c70: 06 11 00 11 01 11 02 11 03 11 04 11 05 11 06 12
|
||||
1c80: 00 12 01 12 02 12 03 12 04 12 05 12 06 13 00 13
|
||||
1c90: 01 13 02 13 03 13 04 13 05 13 06 14 00 14 01 14
|
||||
1ca0: 02 14 03 14 04 14 05 14 06 15 00 15 01 15 02 15
|
||||
1cb0: 03 15 04 15 05 15 06 16 00 16 01 16 02 16 03 16
|
||||
1cc0: 04 16 05 16 06 17 00 17 01 17 02 17 03 17 04 17
|
||||
1cd0: 05 17 06 18 00 18 01 18 02 18 03 18 04 18 05 18
|
||||
1ce0: 06 19 00 19 01 19 02 19 03 19 04 19 05 19 06 1a
|
||||
1cf0: 00 1a 01 1a 02 1a 03 1a 04 1a 05 1a 06 1b 00 1b
|
||||
|
||||
1d00: 01 1b 02 1b 03 1b 04 18 05 18 06 1c 00 1c 01 1c
|
||||
1d10: 02 1c 03 1c 04 1c 05 1c 06 10 00 10 01 10 02 10
|
||||
1d20: 03 10 04 10 05 10 06 1e 00 1e 01 1e 02 1f 03 1f
|
||||
1d30: 04 1e 05 1e 06 1f 00 1f 01 1f 02 1f 03 1f 04 1f
|
||||
1d40: 05 1f 06 20 00 20 01 20 02 20 03 20 04 20 05 20
|
||||
1d50: 06 21 00 21 01 21 02 21 03 21 04 21 05 21 06 22
|
||||
1d60: 00 22 01 22 02 22 03 22 04 22 05 22 06 23 00 23
|
||||
1d70: 01 23 02 23 03 23 04 23 05 23 06 24 00 24 01 24
|
||||
1d80: 02 24 03 24 04 24 05 24 06 25 00 25 01 25 02 25
|
||||
1d90: 03 25 04 25 05 25 06 26 00 26 01 26 02 26 03 26
|
||||
1da0: 04 26 05 26 06 27 00 27 01 27 02 27 03 27 04 27
|
||||
1db0: 05 27 06 00 00 00 00 00 00 00 00 80 80 80 80 80
|
||||
1dc0: 80 80 80 00 00 00 00 00 00 00 00 80 80 80 80 80
|
||||
1dd0: 80 80 80 00 00 00 00 00 00 00 00 80 80 80 80 80
|
||||
1de0: 80 80 80 00 00 00 00 00 00 00 00 80 80 80 80 80
|
||||
1df0: 80 80 80 28 28 28 28 28 28 28 28 a8 a8 a5 a5 a5
|
||||
|
||||
1e00: a8 a8 a8 28 28 28 28 28 28 28 28 a8 a8 a8 a8 a8
|
||||
1e10: a5 a8 a8 28 28 28 28 28 28 28 28 a5 a8 a5 a5 a5
|
||||
1e20: a5 a5 a8 28 28 28 28 28 28 28 28 a8 a5 a8 a8 a8
|
||||
1e30: a8 a8 a5 50 50 50 50 50 50 50 50 d0 00 00 d0 d0
|
||||
1e40: d0 d0 d0 50 50 50 50 50 50 50 50 d0 d0 d0 d0 d0
|
||||
1e50: 00 00 00 50 50 50 50 50 50 50 50 00 d0 dd d0 d0
|
||||
1e60: d0 d0 d0 50 50 50 50 50 50 50 50 d0 d0 d0 d0 d0
|
||||
1e70: d0 d0 d0 20 24 28 2c 30 34 38 3c 20 24 28 2c 30
|
||||
1e80: 34 38 3c 21 25 29 20 31 35 39 3d 21 25 29 20 31
|
||||
1e90: 35 39 30 22 26 2a 26 32 36 3a 3e 22 26 2a 2f 32
|
||||
1ea0: 36 3a 3e 23 27 29 2f 33 37 3b 3f 23 27 2b 2f 33
|
||||
1eb0: 37 3b 36 20 24 28 2c 30 34 38 3c 20 24 28 2c 30
|
||||
1ec0: 34 38 3c 21 25 29 20 31 35 39 3d 21 25 29 20 31
|
||||
1ed0: 35 39 3d 22 26 2a 2e 32 36 3a 3e 22 26 2a 26 32
|
||||
1ee0: 36 3a 36 23 27 2b 2f 33 37 3b 3f 23 27 2b 2f 33
|
||||
1ef0: 37 38 36 20 24 28 2c 30 34 35 3c 20 24 28 2c 30
|
||||
|
||||
1f00: 34 38 3c 21 25 29 20 31 35 39 3d 21 25 29 2d 31
|
||||
1f10: 35 39 3d 22 26 2a 2e 32 36 3a 3e 22 26 2a 2e 32
|
||||
1f20: 36 3a 36 23 27 28 2f 33 37 3b 3f 23 27 2b 2f 33
|
||||
1f30: 37 38 3f
|
||||
|
||||
|
||||
|
||||
Listing 3: This shape-editor program forms a shape table
|
||||
directly from a high-resolution screen image.
|
||||
|
||||
100 TEXT:HOME:POKE-16298,0:POKE-16300,0
|
||||
110 RESTORE:FOR I=768 TO 774:READ J:POKE I,J:NEXT I:POKE 232,0:POKE 233,3:DATA1,0,3,0,45,5,0
|
||||
120 DIM S%(105),T%(212)
|
||||
130 XMAX=42:YMAX=35:ML=101:MT=10
|
||||
140 H$="0123456789ABCDEF"
|
||||
150 D$=CHR$(4)
|
||||
160 GOSUB 3100:GOSUB 3300:GOSUB 3400
|
||||
400 REM SHOW CURSOR POSITION ON GRID
|
||||
410 XDRAW 1 AT CL+1,CT+3
|
||||
420 REM WAIT FOR KEYBOARD COMMAND
|
||||
430 Q=PEEK(-16384):IF Q<128 THEN 430
|
||||
440 POKE-16368,0:Q=Q-128
|
||||
500 REM
|
||||
501 REM CURSOR MOVEMENT COMMANDS
|
||||
502 REM
|
||||
510 IF Q<>ASC("I") THEN 550
|
||||
520 XDRAW 1 AT CL+1,CT+3
|
||||
530 IF Y>1 THEN Y=Y-1:CT=CT-4
|
||||
540 GOTO 410
|
||||
550 IF Q<>ASC("M") THEN 590
|
||||
560 XDRAW 1 AT CL+1,CT+3
|
||||
570 IF Y<YMAX THEN Y=Y+1:CT=CT+4
|
||||
580 GOTO 410
|
||||
590 IF Q<>ASC("J") THEN 630
|
||||
600 XDRAW 1 AT CL+1,CT+3
|
||||
610 IF X>1 THEN X=X-1:CL=CL-4
|
||||
620 GOTO 410
|
||||
630 IF Q<>ASC("K") THEN 700
|
||||
640 XDRAW 1 AT CL+1,CT+3
|
||||
650 IF X<XMAX THEN X=X+1:CL=CL+4
|
||||
660 GOTO 410
|
||||
700 REM
|
||||
701 REM PLOT COMMAND
|
||||
702 REM
|
||||
710 IF Q<>ASC("P") THEN 810
|
||||
720 ELE=INT((X-1)/14)+3*(Y-1)
|
||||
730 BIT=(X-1)-INT((X-1)/14)*14
|
||||
740 A=INT(S%(ELE)/2^BIT)
|
||||
750 IF A/2<>INT(A/2) THEN 810
|
||||
760 S%(ELE)=S%(ELE)+2^BIT
|
||||
770 FOR I=2 TO 4:XDRAW 1 AT CL+1,CT+I:NEXT I
|
||||
780 HCOLOR=3:HPLOT 29+X,62+Y
|
||||
790 GOTO 430
|
||||
800 REM
|
||||
801 REM ERASE COMMAND
|
||||
802 REM
|
||||
810 IF Q<>ASC("E") THEN 900
|
||||
820 ELE=INT((X-1)/14)+3*(Y-1)
|
||||
830 BIT=(X-1)-INT((X-1)/14)*14
|
||||
840 A=INT(S%(ELE)/2^BIT)
|
||||
850 IF A/2=INT(A/2) THEN 900
|
||||
860 S%(ELE)=S%(ELE)-2^BIT
|
||||
870 FOR I=2 TO 4:XDRAW 1 AT CL+1,CT+I:NEXT I
|
||||
880 HCOLOR=0:HPLOT 29+X,62+Y
|
||||
890 GOTO 430
|
||||
900 REM
|
||||
901 REM CLEAR SCREEN COMMAND
|
||||
902 REM
|
||||
910 IF Q<>ASC("C") THEN 1030
|
||||
920 XDRAW 1 AT CL+1,CT+3
|
||||
930 VTAB 23:PRINT"SURE YOU WANT TO ERASE THE SCREEN?"
|
||||
940 GOSUB 3500
|
||||
950 VTAB 22:CALL-958: IF Q<>ASC("Y") THEN 410
|
||||
960 FOR I=0 TO 105:S%(1)=0:NEXT I
|
||||
970 GOSUB 3300:GOSUB 3400:GOTO 410
|
||||
1000 REM
|
||||
1010 REM TABLE COMMAND
|
||||
1020 REM
|
||||
1030 IF Q<>ASC("T") THEN 1520
|
||||
1040 VTAB 23:PRINT"SET CURSOR TO TOP LEFT CORNER OF":PRINT"DESIRED BIT MAP AND HIT RETURN";
|
||||
1050 L5=1
|
||||
1060 GOTO 430
|
||||
1070 PL=X:PT=Y
|
||||
1080 VTAB 22: CALL-958:PRINT:PRINT"SET CURSOR TO BOTTOM RIGHT CORNER OF":PRINT"DESIRED BIT MAP AND HIT RETURN";
|
||||
1090 L5=2
|
||||
1100 GOTO 430
|
||||
1110 PR=X:PB=Y:L5=0
|
||||
1120 XDRAW 1 AT CL+1,CT+3
|
||||
1130 VTAB 22:CALL-958
|
||||
1140 IF PL>PR OR PT>PB THEN VTAB 23:HTAB 1:POKE 50,63:PRINT"ILLEGAL BIT MAP CORNERS":POKE 50,255:FOR I=1 TO 2000:NEXT I:VTAB 22:CALL-958:GOTO 410
|
||||
1150 VTAB 23:HTAB 1:PRINT"NOW FORMING SHAPE TABLE"
|
||||
1160 FOR I=0 TO 212:T%(I)=0:NEXT I
|
||||
1170 L=PB-PT+1:W=(PR-PL+1)/7:IF W<>INT(W) THEN W=INT(W)+1
|
||||
1180 T%(0)=L:T%(1)=W:N=2:Q=0
|
||||
1190 FOR Y=PT TO PB
|
||||
1200 FOR X=PL TO PL+W*7-1
|
||||
1210 IF X>PR THEN BN=0:GOTO 1250
|
||||
1220 ELE=INT((X-1)/14)+3*(Y-1)
|
||||
1230 BIT=(X-1)-INT((X-1)/14)*14
|
||||
1240 BN=0:A=INT(S%(ELE)/2^BIT):IF INT(A/2)<>A/2 THEN BN=1
|
||||
1250 IF BN=1 THEN T%(N)=T%(N)+2^Q
|
||||
1260 Q=Q+1:IF Q=7 THEN Q=0:N=N+1
|
||||
1270 NEXT X:NEXT Y
|
||||
1280 HOME:POKE-16303,0
|
||||
1290 VTAB 2:PRINT"DO YOU WANT TO SEE THE TABLE IN HEX":PRINT" OR IN DECIMAL?":PRINT:PRINT
|
||||
1300 GOSUB 3500
|
||||
1310 IF Q<>ASC("D") AND Q<>ASC("H") THEN 1280
|
||||
1320 Z=0:FOR I=0 TO L*W+1
|
||||
1330 Z=Z+1
|
||||
1340 IF Q=ASC("D") THEN PRINT TAB(Z*4);T%(I);:GOTO 1360
|
||||
1350 PRINT TAB(Z*3);MID$(H$,INT(T%(1)/16)+1,1);MID$(H$,T%(I)-INT(T%(I)/16)*16+1,1);
|
||||
1360 IF Z=8 THEN Z=0:PRINT
|
||||
1370 NEXT I
|
||||
1380 PRINT:PRINT:IF PEEK(37)<21 THEN POKE 34,PEEK(17)
|
||||
1390 PRINT"DO YOU WANT TO SAVE THE OBJECT TABLE":PRINT" ON DISK?"
|
||||
1400 GOSUB 3500
|
||||
1410 IF Q<>ASC("Y") THEN 1470
|
||||
1420 PRINT:PRINT"WHAT DO YOU WANT TO NAME":INPUT" THE FILE? ";N$
|
||||
1430 FOR I=0 TO L*W+1:POKE 16384+I,T%(I):NEXT I
|
||||
1440 PRINT D$;"BSAVE";N$;",A$4000,L";L*W+2
|
||||
1450 PRINT"FILE SAVED USING NAME ";N$
|
||||
1460 PRINT:PRINT:GOTO 1390
|
||||
1470 POKE 34,0:HOME:VTAB 2:PRINT"DO YOU WANT TO RETURN TO THE":PRINT"SCREEN EDIT MODE?"
|
||||
1480 GOSUB 3500
|
||||
1490 IF Q<>ASC("Y") THEN 2260
|
||||
1500 GOSUB 3100:POKE-16304,0:GOSUB 3310:GOTO 410
|
||||
1510 REM 'RETURN' PSEUDO-COMMAND
|
||||
1520 IF Q<>13 THEN 1600
|
||||
1530 ON L5+1 GOTO 430,1070,1110
|
||||
1600 REM
|
||||
1601 REM SAVE TABLE COMMAND
|
||||
1602 REM
|
||||
1610 IF Q<>ASC("S") THEN 1800
|
||||
1620 XDRAW 1 AT CL+1,CT+3
|
||||
1630 VTAB 23:INPUT"FILE NAME FOR SAVE? ";N$
|
||||
1640 VTAB 24:PRINT"NOW SCANNING IMAGE";:HTAB 1
|
||||
1650 Z1=0
|
||||
1660 IF S%(Z1)=0 AND Z1<105 THEN Z1=Z1+1:GOTO 1660
|
||||
1670 Z2=105
|
||||
1680 IF S%(Z2)=0 AND Z2>0 THEN Z2=Z2-1:GOTO 1680
|
||||
1690 IF Z1>Z2 THEN Z1=0:Z2=1
|
||||
1700 VTAB 24:PRINT"NOW SAVING IMAGE TO DISK";:VTAB 23:PRINT
|
||||
1710 PRINT D$;"OPEN";N$:PRINT D$;"WRITE";N$
|
||||
1720 PRINT Z1:PRINT Z2
|
||||
1730 FOR I=Z1 TO Z2
|
||||
1740 PRINT S%(I)
|
||||
1750 NEXT I
|
||||
1760 PRINT D$;"CLOSE";N$
|
||||
1770 VTAB 22:CALL-958:GOTO 410
|
||||
1800 REM
|
||||
1801 REM LOAD TABLE COMMAND
|
||||
1802 REM
|
||||
1810 IF Q<>ASC("G") THEN 2100
|
||||
1820 XDRAW 1 AT CL+1,CT+3
|
||||
1830 VTAB 23:PRINT"SURE YOU WANT TO LOAD?"
|
||||
1840 GOSUB 3500
|
||||
1850 VTAB 22:CALL-958:IF Q<>ASC("Y") THEN 410
|
||||
1860 VTAB 23:INPUT"FILE NAME FOR LOAD? ";N$
|
||||
1870 PRINT D$;"OPEN"N$:PRINT D$;"READ";N$
|
||||
1880 INPUT Z1:INPUT Z2
|
||||
1890 FOR I=0 TO Z1:S%(I)=0:NEXT I:FOR I=Z2 TO 105:S%(I)=0:NEXT I
|
||||
1900 FOR I=Z1 TO Z2
|
||||
1910 INPUT S%(I)
|
||||
1920 NEXT I
|
||||
1930 PRINT D$;"CLOSE";N%
|
||||
1940 GOSUB 3300: GOSUB 3400
|
||||
1950 VTAB 22:CALL-958:VTAB 23:PRINT"NOW RETRACING IMAGE ON SCREEN"
|
||||
1960 ELE=Z1:BIT=0:CL=ML+4*((ELE-INT(ELE/3)*3)*14)
|
||||
1970 CT=MT+4*INT(ELE/3)
|
||||
1980 A=INT(S%(ELE)/2^BIT): IF INT(A/2)=A/2 THEN 2000
|
||||
1990 FOR I=2 TO 4:XDRAW 1 AT CL+1,CT+I:NEXT I:HPLOT 30+(CL-ML)/4,63+(CT-MT)/4
|
||||
2000 CL=CL+4:BIT=BIT+1:IF BIT<>14 THEN 1980
|
||||
2010 IF ELE>=Z2 THEN GOSUB 3310:GOTO 410
|
||||
2020 BIT=0:ELE=ELE+1
|
||||
2030 IF ELE/3=INT(ELE/3) THEN CL=ML:CT=CT+4
|
||||
2040 GOTO 1980
|
||||
2100 REM
|
||||
2101 REM HELP COMMAND
|
||||
2102 REM
|
||||
2110 IF Q<>ASC("H") AND Q<>ASC("/") AND Q<>ASC("?") THEN 2200
|
||||
2120 VTAB21:CALL-958:POKE-16303,0
|
||||
2130 GOSUB 3170
|
||||
2140 POKE-16304,0
|
||||
2150 VTAB 20:PRINT:CALL-958:HTAB 2:PRINT"ACTUAL SIZE";:HTAB 21:PRINT"VIEWING WINDOW"
|
||||
2160 GOTO 430
|
||||
2200 REM
|
||||
2201 REM QUIT OMMAND
|
||||
2202 REM
|
||||
2210 IF Q<>ASC("Q") THEN 430
|
||||
2220 XDRAW 1 AT CL+1,CT+3
|
||||
2230 VTAB 23:PRINT"SURE YOU WANT TO QUIT?"
|
||||
2240 GOSUB 3500
|
||||
2250 IF Q<>ASC("Y") THEN VTAB 22:CALL-958:GOTO 410
|
||||
2260 HOME:POKE-16303,0:POKE-16298,0:VTAB 24
|
||||
2270 GOTO 9999
|
||||
3000 REM
|
||||
3010 REM SUBROUTINES
|
||||
3320 REM
|
||||
3100 HOME
|
||||
3110 HTAB 15:PRINT"COMMAND MENU":HTAB 15:PRINT"------- ----"
|
||||
3120 VTAB 4:PRINT"I,J,K,M"; TAB(9);"CURSOR MOVEMENT":PRINT:PRINT"P";TAB(9);"PLOT POINT AT CURSOR POSITION":PRINT
|
||||
3130 PRINT"E";TAB(9);"ERASE POINT AT CURSOR POSITION":PRINT:PRINT"C";TAB(9);"CLEAR SCREEN":PRINT
|
||||
3140 PRINT"T";TAB(9);"MAKE SHAPE TABLE":PRINT:PRINT"S";TAB(9);"SAVE SHAPE SOURCE FILE TO DISK":PRINT
|
||||
3150 PRINT"G";TAB(9);"GET SHAPE SOURCE FILE FROM DISK":PRINT:PRINT"H OR ?";TAB(9);"HELP (RETURN TO THIS MENU)":PRINT
|
||||
3160 PRINT:PRINT"Q";TAB(9);"QUIT PROGRAM EXECUTION"
|
||||
3170 VTAB 24:HTAB 10:PRINT"HIT SPACE TO EXIT MENU";
|
||||
3180 GOSUB 3500:IF Q<>ASC(" ") THEN 3180
|
||||
3190 VTAB 21:CALL-958
|
||||
3200 RETURN
|
||||
3300 POKE 230,32:CALL 62450:HGR:SCALE=1:ROT=0
|
||||
3310 PT=YMAX+1:PB=0:PL=XMAX+1:PR=0
|
||||
3320 VTAB 20:PRINT:CALL-958:HTAB 2:PRINT"ACTUAL SIZE";:HTAB 21:PRINT"VIEWING WINDOW"
|
||||
REM 3320 VTAB 21:HTAB 2:PRINT"ACTUAL SIZE";:HTAB 21:PRINT"VIEWING WINDOW";:CALL-958:PRINT
|
||||
3330 X=INT(XMAX/2):Y=INT(YMAX/2)
|
||||
3340 MR=ML+XMAX*4:MB=MT+YMAX*4
|
||||
3350 CL=ML+(X-1)*4:CT=MT+(Y-1)*4
|
||||
3360 RETURN
|
||||
3400 HCOLOR=3
|
||||
3410 FOR I=ML TO MR STEP 4:HPLOT I,MT TO I,MB:NEXT I
|
||||
3420 FOR I=MT TO MB STEP 4:HPLOT ML,I TO MR,I:NEXT I
|
||||
3430 RETURN
|
||||
3500 Q=PEEK(-16384):IF Q<128 THEN 3500
|
||||
3510 POKE-16368,0:Q=Q-128
|
||||
3520 RETURN
|
||||
9999 END
|
||||
|
||||
|
||||
|
||||
Table 1: Summary of parameters that must be set up prior to
|
||||
calling the shape subroutine: coordinates of upper left
|
||||
corner of bit picture (1a) and starting address
|
||||
(hexadecimal) of shape table (1b).
|
||||
|
||||
(1a)
|
||||
Coordinate 6502 Register
|
||||
|
||||
x low-order byte X
|
||||
x high-order byte Y
|
||||
y A
|
||||
|
||||
(1b)
|
||||
Address Byte Memory Location
|
||||
|
||||
low-order byte EB
|
||||
high-order byte EC
|
||||
|
||||
|
||||
|
||||
Photo 1: The command menu that appears at the beginning of
|
||||
the shape-editor program (listing 3). This menu also appears
|
||||
whenever the Help key is pressed.
|
||||
|
||||
+----------------------------------------+
|
||||
| COMMAND MENU |
|
||||
| ------- ---- |
|
||||
| |
|
||||
|I,J,K,M CURSOR MOVEMENT |
|
||||
| |
|
||||
|P PLOT POINT AT CURSOR POSITION |
|
||||
| |
|
||||
|E ERASE POINT AT CURSOR POSITION |
|
||||
| |
|
||||
|C CLEAR SCREEN |
|
||||
| |
|
||||
|T MAKE SHAPE TABLE |
|
||||
| |
|
||||
|S SAVE SHAPE SOURCE FILE TO DISK |
|
||||
| |
|
||||
|G GET SHAPE SOURCE FILE FROM DISK |
|
||||
| |
|
||||
|H OR ? HELP (RETURN TO THIS MENU) |
|
||||
| |
|
||||
| |
|
||||
|Q QUIT PROGRAM EXECUTION |
|
||||
| |
|
||||
| |
|
||||
| HIT SPACE TO EXIT MENU |
|
||||
+----------------------------------------+
|
||||
|
||||
|
||||
|
||||
Photo 2: A view of the screen-edit mode of the shape-editor
|
||||
program. The figure on the grid is an enlarged view of the
|
||||
actual-size shape on the left side of the screen. The cursor
|
||||
is the small horizontal line in a square above the lower
|
||||
left corner of the displayed shape.
|
||||
|
||||
|
||||
|
||||
Photo 3: A view of the first step in forming a shape table.
|
||||
The desired shape is selected by defining a rectangle
|
||||
enclosing the shape. Here, the user has positioned the
|
||||
cursor to the correct position to define the upper left
|
||||
corner of the rectangle.
|
||||
|
||||
|
||||
|
||||
Photo 4: A view of the screen after the shape-editor program
|
||||
has formed the shape table for the shape shown in photo 3.
|
||||
|
||||
+----------------------------------------+
|
||||
| |
|
||||
| |
|
||||
|DO YOU WANT TO SEE THE TABLE IN HEX |
|
||||
| OR IN DECIMAL? |
|
||||
| |
|
||||
| 08 02 70 07 04 88 12 12 |
|
||||
| 01 29 79 27 01 20 7F 3F |
|
||||
| 00 04 00 04 00 04 0E 1C |
|
||||
| |
|
||||
|DO YOU WANT TO SAVE THE OBJECT TABLE |
|
||||
| ON DISK? |
|
||||
| |
|
||||
|WHAT DO YOU WANT TO NAME |
|
||||
| THE FILE? |
|
||||
| |
|
||||
| |
|
||||
+----------------------------------------+
|
||||
|
||||
|
||||
Reference in New Issue
Block a user