mirror of
https://github.com/irmen/prog8.git
synced 2024-12-29 04:29:19 +00:00
245 lines
7.2 KiB
Lua
245 lines
7.2 KiB
Lua
%target c64
|
|
%import textio
|
|
|
|
; bitmap pixel graphics module for the C64
|
|
; only black/white monchrome 320x200 for now
|
|
; assumes bitmap screen memory is $2000-$3fff
|
|
|
|
graphics {
|
|
const uword BITMAP_ADDRESS = $2000
|
|
const uword WIDTH = 320
|
|
const ubyte HEIGHT = 200
|
|
|
|
sub enable_bitmap_mode() {
|
|
; enable bitmap screen, erase it and set colors to black/white.
|
|
c64.SCROLY |= %00100000
|
|
c64.VMCSB = (c64.VMCSB & %11110000) | %00001000 ; $2000-$3fff
|
|
clear_screen(1, 0)
|
|
}
|
|
|
|
sub clear_screen(ubyte pixelcolor, ubyte bgcolor) {
|
|
memset(BITMAP_ADDRESS, 320*200/8, 0)
|
|
txt.fill_screen(pixelcolor << 4 | bgcolor, 0)
|
|
}
|
|
|
|
sub line(uword @zp x1, ubyte @zp y1, uword @zp x2, ubyte @zp y2) {
|
|
; Bresenham algorithm.
|
|
; This code special cases various quadrant loops to allow simple ++ and -- operations.
|
|
; TODO rewrite this in optimized assembly
|
|
if y1>y2 {
|
|
; make sure dy is always positive to avoid 8 instead of just 4 special cases
|
|
swap(x1, x2)
|
|
swap(y1, y2)
|
|
}
|
|
word @zp d = 0
|
|
ubyte positive_ix = true
|
|
word @zp dx = x2-x1 as word
|
|
word @zp dy = y2-y1
|
|
if dx < 0 {
|
|
dx = -dx
|
|
positive_ix = false
|
|
}
|
|
dx *= 2
|
|
dy *= 2
|
|
internal_plotx = x1
|
|
|
|
if dx >= dy {
|
|
if positive_ix {
|
|
repeat {
|
|
internal_plot(y1)
|
|
if internal_plotx==x2
|
|
return
|
|
internal_plotx++
|
|
d += dy
|
|
if d > dx {
|
|
y1++
|
|
d -= dx
|
|
}
|
|
}
|
|
} else {
|
|
repeat {
|
|
internal_plot(y1)
|
|
if internal_plotx==x2
|
|
return
|
|
internal_plotx--
|
|
d += dy
|
|
if d > dx {
|
|
y1++
|
|
d -= dx
|
|
}
|
|
}
|
|
}
|
|
}
|
|
else {
|
|
if positive_ix {
|
|
repeat {
|
|
internal_plot(y1)
|
|
if y1 == y2
|
|
return
|
|
y1++
|
|
d += dx
|
|
if d > dy {
|
|
internal_plotx++
|
|
d -= dy
|
|
}
|
|
}
|
|
} else {
|
|
repeat {
|
|
internal_plot(y1)
|
|
if y1 == y2
|
|
return
|
|
y1++
|
|
d += dx
|
|
if d > dy {
|
|
internal_plotx--
|
|
d -= dy
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
sub circle(uword xcenter, ubyte ycenter, ubyte radius) {
|
|
; Midpoint algorithm
|
|
ubyte @zp ploty
|
|
ubyte @zp xx = radius
|
|
ubyte @zp yy = 0
|
|
byte @zp decisionOver2 = 1-xx as byte
|
|
|
|
while xx>=yy {
|
|
internal_plotx = xcenter + xx
|
|
ploty = ycenter + yy
|
|
internal_plot(ploty)
|
|
internal_plotx = xcenter - xx
|
|
internal_plot(ploty)
|
|
internal_plotx = xcenter + xx
|
|
ploty = ycenter - yy
|
|
internal_plot(ploty)
|
|
internal_plotx = xcenter - xx
|
|
internal_plot(ploty)
|
|
internal_plotx = xcenter + yy
|
|
ploty = ycenter + xx
|
|
internal_plot(ploty)
|
|
internal_plotx = xcenter - yy
|
|
internal_plot(ploty)
|
|
internal_plotx = xcenter + yy
|
|
ploty = ycenter - xx
|
|
internal_plot(ploty)
|
|
internal_plotx = xcenter - yy
|
|
internal_plot(ploty)
|
|
yy++
|
|
if decisionOver2<=0
|
|
decisionOver2 += 2*yy+1
|
|
else {
|
|
xx--
|
|
decisionOver2 += 2*(yy-xx)+1
|
|
}
|
|
}
|
|
}
|
|
|
|
sub disc(uword xcenter, ubyte ycenter, ubyte radius) {
|
|
; Midpoint algorithm, filled
|
|
ubyte xx = radius
|
|
ubyte yy = 0
|
|
byte decisionOver2 = 1-xx as byte
|
|
|
|
while xx>=yy {
|
|
ubyte ycenter_plus_yy = ycenter + yy
|
|
ubyte ycenter_min_yy = ycenter - yy
|
|
ubyte ycenter_plus_xx = ycenter + xx
|
|
ubyte ycenter_min_xx = ycenter - xx
|
|
|
|
for internal_plotx in xcenter to xcenter+xx {
|
|
internal_plot(ycenter_plus_yy)
|
|
internal_plot(ycenter_min_yy)
|
|
}
|
|
for internal_plotx in xcenter-xx to xcenter-1 {
|
|
internal_plot(ycenter_plus_yy)
|
|
internal_plot(ycenter_min_yy)
|
|
}
|
|
for internal_plotx in xcenter to xcenter+yy {
|
|
internal_plot(ycenter_plus_xx)
|
|
internal_plot(ycenter_min_xx)
|
|
}
|
|
for internal_plotx in xcenter-yy to xcenter {
|
|
internal_plot(ycenter_plus_xx)
|
|
internal_plot(ycenter_min_xx)
|
|
}
|
|
yy++
|
|
if decisionOver2<=0
|
|
decisionOver2 += 2*yy+1
|
|
else {
|
|
xx--
|
|
decisionOver2 += 2*(yy-xx)+1
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
; here is the non-asm code for the plot routine below:
|
|
; sub plot_nonasm(uword px, ubyte py) {
|
|
; ubyte[] ormask = [128, 64, 32, 16, 8, 4, 2, 1]
|
|
; uword addr = BITMAP_ADDRESS + 320*(py>>3) + (py & 7) + (px & %0000000111111000)
|
|
; @(addr) |= ormask[lsb(px) & 7]
|
|
; }
|
|
|
|
asmsub plot(uword plotx @XY, ubyte ploty @A) clobbers (A, X, Y) {
|
|
%asm {{
|
|
stx internal_plotx
|
|
sty internal_plotx+1
|
|
jmp internal_plot
|
|
}}
|
|
}
|
|
|
|
; for efficiency of internal algorithms here is the internal plot routine
|
|
; that takes the plotx coordinate in a separate variable instead of the XY register pair:
|
|
|
|
uword internal_plotx ; 0..319 ; separate 'parameter' for internal_plot()
|
|
|
|
asmsub internal_plot(ubyte ploty @A) clobbers (A, X, Y) { ; internal_plotx is 16 bits 0 to 319... doesn't fit in a register
|
|
%asm {{
|
|
tay
|
|
lda internal_plotx+1
|
|
sta P8ZP_SCRATCH_W2+1
|
|
lsr a ; 0
|
|
sta P8ZP_SCRATCH_W2
|
|
lda internal_plotx
|
|
pha
|
|
and #7
|
|
tax
|
|
|
|
lda _y_lookup_lo,y
|
|
clc
|
|
adc P8ZP_SCRATCH_W2
|
|
sta P8ZP_SCRATCH_W2
|
|
lda _y_lookup_hi,y
|
|
adc P8ZP_SCRATCH_W2+1
|
|
sta P8ZP_SCRATCH_W2+1
|
|
|
|
pla ; internal_plotx
|
|
and #%11111000
|
|
tay
|
|
lda (P8ZP_SCRATCH_W2),y
|
|
ora _ormask,x
|
|
sta (P8ZP_SCRATCH_W2),y
|
|
rts
|
|
|
|
_ormask .byte 128, 64, 32, 16, 8, 4, 2, 1
|
|
|
|
; note: this can be even faster if we also have a 256 byte x-lookup table, but hey.
|
|
; see http://codebase64.org/doku.php?id=base:various_techniques_to_calculate_adresses_fast_common_screen_formats_for_pixel_graphics
|
|
; the y lookup tables encodes this formula: BITMAP_ADDRESS + 320*(py>>3) + (py & 7) (y from 0..199)
|
|
; We use the 64tass syntax for range expressions to calculate this table on assembly time.
|
|
|
|
_plot_y_values := $2000 + 320*(range(200)>>3) + (range(200) & 7)
|
|
|
|
_y_lookup_lo .byte <_plot_y_values
|
|
_y_lookup_hi .byte >_plot_y_values
|
|
|
|
}}
|
|
}
|
|
|
|
}
|
|
|
|
|