prog8/compiler/res/prog8lib/cx16/graphics.p8

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%target cx16
%import syslib
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%import textio
; bitmap pixel graphics module for the CommanderX16
; wraps the graphics functions that are in ROM.
; only black/white monchrome 320x200 for now.
graphics {
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const uword WIDTH = 320
const ubyte HEIGHT = 200
sub enable_bitmap_mode() {
; enable bitmap screen, erase it and set colors to black/white.
void cx16.screen_set_mode($80)
cx16.r0 = 0
cx16.GRAPH_init()
clear_screen(1, 0)
}
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sub disable_bitmap_mode() {
; enables text mode, erase the text screen, color white
void cx16.screen_set_mode(2)
txt.fill_screen(' ', 1) ; doesn't seem to fully clear the text screen after returning from gfx mode
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}
sub clear_screen(ubyte pixelcolor, ubyte bgcolor) {
cx16.GRAPH_set_colors(pixelcolor, pixelcolor, bgcolor)
cx16.GRAPH_clear()
}
sub line(uword @zp x1, ubyte @zp y1, uword @zp x2, ubyte @zp y2) {
cx16.r0 = x1
cx16.r1 = y1
cx16.r2 = x2
cx16.r3 = y2
cx16.GRAPH_draw_line()
}
sub circle(uword xcenter, ubyte ycenter, ubyte radius) {
;cx16.r0 = xcenter - radius/2
;cx16.r1 = ycenter - radius/2
;cx16.r2 = radius*2
;cx16.r3 = radius*2
;cx16.GRAPH_draw_oval(false) ; currently this call is not implemented on cx16, does a BRK
; Midpoint algorithm
ubyte @zp xx = radius
ubyte @zp yy = 0
byte @zp decisionOver2 = 1-xx as byte
while xx>=yy {
cx16.r0 = xcenter + xx
cx16.r1 = ycenter + yy
cx16.FB_cursor_position()
cx16.FB_set_pixel(1)
cx16.r0 = xcenter - xx
cx16.FB_cursor_position()
cx16.FB_set_pixel(1)
cx16.r0 = xcenter + xx
cx16.r1 = ycenter - yy
cx16.FB_cursor_position()
cx16.FB_set_pixel(1)
cx16.r0 = xcenter - xx
cx16.FB_cursor_position()
cx16.FB_set_pixel(1)
cx16.r0 = xcenter + yy
cx16.r1 = ycenter + xx
cx16.FB_cursor_position()
cx16.FB_set_pixel(1)
cx16.r0 = xcenter - yy
cx16.FB_cursor_position()
cx16.FB_set_pixel(1)
cx16.r0 = xcenter + yy
cx16.r1 = ycenter - xx
cx16.FB_cursor_position()
cx16.FB_set_pixel(1)
cx16.r0 = xcenter - yy
cx16.FB_cursor_position()
cx16.FB_set_pixel(1)
yy++
if decisionOver2<=0 {
decisionOver2 += 2*yy+1
} else {
xx--
decisionOver2 += 2*(yy-xx)+1
}
}
}
sub disc(uword xcenter, ubyte ycenter, ubyte radius) {
; cx16.r0 = xcenter - radius/2
; cx16.r1 = ycenter - radius/2
; cx16.r2 = radius*2
; cx16.r3 = radius*2
; cx16.GRAPH_draw_oval(true) ; currently this call is not implemented on cx16, does a BRK
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
uword @zp plotx
cx16.r0 = xcenter-xx
cx16.r1 = ycenter_plus_yy
cx16.FB_cursor_position()
repeat xx*2+1
cx16.FB_set_pixel(1)
cx16.r0 = xcenter-xx
cx16.r1 = ycenter_min_yy
cx16.FB_cursor_position()
repeat xx*2+1
cx16.FB_set_pixel(1)
cx16.r0 = xcenter-yy
cx16.r1 = ycenter_plus_xx
cx16.FB_cursor_position()
repeat yy*2+1
cx16.FB_set_pixel(1)
cx16.r0 = xcenter-yy
cx16.r1 = ycenter_min_xx
cx16.FB_cursor_position()
repeat yy*2+1
cx16.FB_set_pixel(1)
yy++
if decisionOver2<=0
decisionOver2 += 2*yy+1
else {
xx--
decisionOver2 += 2*(yy-xx)+1
}
}
}
sub plot(uword plotx, ubyte ploty) {
cx16.r0 = plotx
cx16.r1 = ploty
cx16.FB_cursor_position()
cx16.FB_set_pixel(1)
}
}