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Removed some tests.
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jespergravgaard
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d67749719e
@ -1,41 +0,0 @@
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### Line Buffer
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Used for rendering lines into. Organized with linear addressed columns of 8 bits, allowing the line routine to addess the y-coordinate using X/Y-addressing.
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### Screen Buffer
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Used for filling & showing to the user. There are 2 screen buffers allowing for double buffering.
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Memory organization is be adapted to the specific display. This means the same line routines can be used for charsets, bitmaps, sprites etc.
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### Algorithm
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1. Move points
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2. Clear line buffer
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3. Render lines into line buffer
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4. Wait for screen buffer being available for rendering (mostly instant)
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5. EOR-fill from line buffer into screen buffer
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6. Mark screen buffer for showing, swap screen buffer
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### Line Drawing
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Optimized line drawing routines for the 8 different cases. (xd positive/negative, yd , xd-yd positive/negative)
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- Lines are organized in a clockwise fashion ensuring that xd positive means the fill starts and xd negative means the fill ends.
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- xd positive (start fill): steep slope lines render the top-most pixel, flat slope lines render the actual pixel.
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- xd negative (stop fill): steep slope lines render the pixel below bottom-most pixel, flat slope lines render below the actual pixel.
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- unrolled line routines with code for each individual x-pixel position can plot lines quite fast
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- unrolled line routines can be called by writing an RTS at code of the stop x-position and JSR'ing into the code for the start X-position.
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- The RTS must be fixed again after return.
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### EOR filling
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Unrolled EOR-filler from the line buffer. The screen buffer does not need to be cleared because the filler always fills all bytes.
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### Effective Canvas Shape
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Both the line canvas and screen canvas can benefit from identifying the effective canvas shape where an object can be rendered.
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For instance a freely 3D-rotated object may only occupy a circular shaped canvas.
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By only clearing & filling this effective canvas these time consuming routines arebecome faster.
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It might also be worth dynamically detecting the canvas shape for each rendered frame - to allow even faster clear/fill.
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This will require an efficient way of identifying min/max y-value in for each column that consumes less time than the time saved by not clearing/filling.
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@ -1,267 +0,0 @@
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// Filling a simple 16x16 2D polygon using EOR-filling
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// - Clearing canvas
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// - Trivial 2D rotation using sine tables
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// - Line-drawing polygon edges (fill-ready lines)
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// - Up-to-down EOR filling
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// - Double buffering
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#include <string.h>
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#include <c64.h>
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#include <time.h>
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#include <stdio.h>
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#include <conio.h>
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#undef DEBUG
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// The line buffer
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char* const LINE_BUFFER = 0x2000;
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// The two charsets used as screen buffers
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char* const CANVAS1 = 0x3000;
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char* const CANVAS2 = 0x3800;
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// The screen matrix
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char* const SCREEN = 0x2c00;
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// The screen console
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char* const CONSOLE = 0x0400;
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// The default charset address
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char* const PETSCII = 0x1000;
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// The current canvas being rendered to the screen - in D018 format.
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char volatile canvas_show_memory = toD018(SCREEN, CANVAS2);
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// Flag signalling that the canvas on screen needs to be updated.
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// Set to 1 by the renderer when a new canvas is ready for showing, and to 0 by the raster when the canvas is shown on screen.
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char volatile canvas_show_flag = 0;
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// SIN/COS tables
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char __align(0x100) SINTAB[0x140] = kickasm {{
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.fill $200, round(63 + 63*sin(i*2*PI/$100))
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}};
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char* COSTAB = SINTAB+0x40;
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void main() {
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// Clear the console
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memset(CONSOLE, ' ', 40*25);
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// Clear the screen
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memset(SCREEN, 0, 40*25);
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memset(COLS, BLACK, 40*25);
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// Setup 16x16 canvas for rendering
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char *screen= SCREEN+12, *cols=COLS+12;
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for(char y=0;y<16;y++) {
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char c=y;
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for(char x=0;x<16;x++) {
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cols[x] = WHITE;
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screen[x] = c;
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c+=0x10;
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}
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cols += 40;
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screen += 40;
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}
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VICII->BORDER_COLOR = BLACK;
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VICII->BG_COLOR = BLACK;
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// Set-up the raster IRQ
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setup_irq();
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// Set text color
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textcolor(WHITE);
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char p0_idx = 0xb5;
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char p1_idx = p0_idx+15;
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char p2_idx = p0_idx+170;
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// The current canvas being rendered to
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char* canvas = CANVAS1;
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while(1) {
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clock_start();
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// Clear line buffer
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memset(LINE_BUFFER, 0, 0x0800);
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// Plot in line buffer
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char x0 = COSTAB[p0_idx];
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char y0 = SINTAB[p0_idx];
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char x1 = COSTAB[p1_idx];
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char y1 = SINTAB[p1_idx];
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line(LINE_BUFFER, x0, y0, x1, y1);
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char x2 = COSTAB[p2_idx];
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char y2 = SINTAB[p2_idx];
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line(LINE_BUFFER, x1, y1, x2, y2);
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line(LINE_BUFFER, x2, y2, x0, y0);
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// Move idx
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p0_idx++;
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p1_idx++;
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p2_idx++;
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// Wait until the canvas on screen has been switched before starting work on the next frame
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VICII->BORDER_COLOR = RED;
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while(canvas_show_flag) {}
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VICII->BORDER_COLOR = BLACK;
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// Fill canvas
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eorfill(LINE_BUFFER, canvas);
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// swap canvas being rendered to (using XOR)
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canvas ^= (CANVAS1^CANVAS2);
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// Swap canvas to show on screen (using XOR)
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canvas_show_memory ^= toD018(SCREEN,CANVAS1)^toD018(SCREEN,CANVAS2);
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// Set flag used to signal when the canvas has been shown
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canvas_show_flag = 1;
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// Read and display cycles
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clock_t cyclecount = clock()-CLOCKS_PER_INIT;
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//gotoxy(0,24);
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//printf("frame: %02x cycles: %6lu", p0_idx, cyclecount);
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//printf("(%02x,%02x)-(%02x,%02x)", x0, y0, x1, y1);
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}
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}
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// Setup raster IRQ to change charset at different lines
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void setup_irq() {
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asm { sei }
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// Disable CIA 1 Timer IRQ
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CIA1->INTERRUPT = CIA_INTERRUPT_CLEAR;
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// Set raster line to 8 pixels before the border
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VICII->CONTROL1 &= 0x7f;
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VICII->RASTER = BORDER_YPOS_BOTTOM-8;
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// Enable Raster Interrupt
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VICII->IRQ_ENABLE = IRQ_RASTER;
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// Set the IRQ routine
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*KERNEL_IRQ = &irq_bottom_1;
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asm { cli }
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}
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// Interrupt Routine 1: Just above last text line.
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__interrupt void irq_bottom_1() {
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// Change border color
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VICII->BORDER_COLOR = DARK_GREY;
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// Show the cycle counter
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VICII->MEMORY = toD018(CONSOLE, PETSCII);
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// Acknowledge the IRQ
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VICII->IRQ_STATUS = IRQ_RASTER;
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// Trigger IRQ 2 at bottom of text-line
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VICII->RASTER = BORDER_YPOS_BOTTOM;
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*KERNEL_IRQ = &irq_bottom_2;
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}
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// Interrupt Routine 2
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__interrupt(rom_sys_c64) void irq_bottom_2() {
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// Change border color
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VICII->BORDER_COLOR = BLACK;
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// Show the current canvas (unless a key is being pressed)
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if(!kbhit()) {
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VICII->MEMORY = canvas_show_memory;
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} else {
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VICII->MEMORY = toD018(SCREEN, LINE_BUFFER);
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}
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canvas_show_flag = 0;
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// Acknowledge the IRQ
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VICII->IRQ_STATUS = IRQ_RASTER;
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// Trigger IRQ 1 at 8 pixels before the border
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VICII->RASTER = BORDER_YPOS_BOTTOM-8;
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*KERNEL_IRQ = &irq_bottom_1;
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}
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// Draw a EOR friendly line between two points
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// Uses bresenham line drawing routine
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void line(char* canvas, char x1, char y1, char x2, char y2) {
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char x = x1;
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char y = y1;
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char dx = abs_u8(x2-x1);
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char dy = abs_u8(y2-y1);
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char sx = sgn_u8(x2-x1);
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char sy = sgn_u8(y2-y1);
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// The sign of the x-difference determines if this is a line at the top of the face
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// being filled or a line at the bottom of the face. Because the points are organized in a clockwise
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// fashion any line pointing right is filled below the line and any line pointing left is filled above
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if(sx==0xff) {
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// This is a line at the bottom of the face - move it 1 pixel down to stop the fill correctly
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y++; y2++;
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}
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if(dx > dy) {
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// Flat slope - X is the driver - plot every X using bresenham
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char e = dx/2;
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do {
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plot(x, y);
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x += sx;
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e += dy;
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if(e>dx) {
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y += sy;
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e -= dx;
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}
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} while (x != x2);
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plot(x, y);
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} else {
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// Steep slope - Y is the driver - only plot one plot per X
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if(sx==sy) {
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// If dx/dy signs are identical we must render the first pixel of each segment
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plot(x, y);
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if(dx==0)
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return;
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char e = dy/2;
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do {
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do {
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y += sy;
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e += dx;
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} while(e<=dy);
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x += sx;
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e -= dy;
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plot(x, y);
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} while (x != x2);
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} else {
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// If dx/dy signs differ we must render the last pixel of each segment
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char e = dy/2;
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do {
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y += sy;
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e += dx;
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if(e>dy) {
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plot(x, y-sy);
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x += sx;
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e -= dy;
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}
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} while (y != y2);
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plot(x, y);
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}
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}
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}
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// Column offsets
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char* plot_column[16] = { LINE_BUFFER+0, LINE_BUFFER+1*128, LINE_BUFFER+2*128, LINE_BUFFER+3*128, LINE_BUFFER+4*128, LINE_BUFFER+5*128, LINE_BUFFER+6*128, LINE_BUFFER+7*128, LINE_BUFFER+8*128, LINE_BUFFER+9*128, LINE_BUFFER+10*128, LINE_BUFFER+11*128, LINE_BUFFER+12*128, LINE_BUFFER+13*128, LINE_BUFFER+14*128, LINE_BUFFER+15*128 };
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// The bits used for plotting a pixel
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char plot_bit[8] = { 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01};
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// Plot a single point on the canvas
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inline void plot(char x, char y) {
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// Find the canvas column
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char* column = plot_column[x/8];
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// Plot the bit
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column[y] |= plot_bit[x&7];
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}
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// EOR fill from the line buffer onto the canvas
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void eorfill(char* line_buffer, char* canvas) {
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char* line_column = line_buffer;
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char* fill_column = canvas;
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for(char x=0;x<16;x++) {
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char eor = line_column[0];
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fill_column[0] = eor;
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for(char y=1;y<16*8;y++) {
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eor ^= line_column[y];
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fill_column[y] = eor;
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}
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line_column += 16*8;
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fill_column += 16*8;
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}
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}
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// Get the absolute value of a 8-bit unsigned number treated as a signed number.
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unsigned char abs_u8(unsigned char u) {
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if(u & 0x80) {
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return -u;
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} else {
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return u;
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}
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}
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// Get the sign of a 8-bit unsigned number treated as a signed number.
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// Returns unsigned -1 if the number is negative
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unsigned char sgn_u8(unsigned char u) {
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if(u & 0x80) {
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return -1;
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} else {
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return 1;
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}
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}
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