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https://github.com/irmen/prog8.git
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106 lines
3.1 KiB
Lua
106 lines
3.1 KiB
Lua
%import syslib
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%import graphics
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; Note: this program is compatible with C64 and CX16.
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; TODO why has the prg become bigger since register args?
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main {
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; vertices
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word[] xcoor = [ -100, -100, -100, -100, 100, 100, 100, 100 ]
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word[] ycoor = [ -100, -100, 100, 100, -100, -100, 100, 100 ]
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word[] zcoor = [ -100, 100, -100, 100, -100, 100, -100, 100 ]
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; storage for rotated coordinates
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word[len(xcoor)] rotatedx
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word[len(ycoor)] rotatedy
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word[len(zcoor)] rotatedz
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; edges
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ubyte[] edgesFrom = [ 0, 2, 6, 4, 1, 3, 7, 5, 0, 2, 6, 4]
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ubyte[] edgesTo = [ 2, 6, 4, 0, 3, 7, 5, 1, 1, 3, 7, 5]
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sub start() {
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uword anglex
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uword angley
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uword anglez
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graphics.enable_bitmap_mode()
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repeat {
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rotate_vertices(msb(anglex), msb(angley), msb(anglez))
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graphics.clear_screen(1, 0)
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draw_lines()
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anglex-=500
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angley+=217
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anglez+=452
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wait_a_little_bit()
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}
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}
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sub wait_a_little_bit() {
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%asm {{
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stx P8ZP_SCRATCH_REG
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lda #0
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jsr c64.SETTIM
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- jsr c64.RDTIM
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cmp #1
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bne -
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ldx P8ZP_SCRATCH_REG
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rts
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}}
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}
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sub rotate_vertices(ubyte ax, ubyte ay, ubyte az) {
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; rotate around origin (0,0,0)
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; set up the 3d rotation matrix values
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word wcosa = cos8(ax)
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word wsina = sin8(ax)
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word wcosb = cos8(ay)
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word wsinb = sin8(ay)
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word wcosc = cos8(az)
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word wsinc = sin8(az)
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word wcosa_sinb = wcosa*wsinb / 128
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word wsina_sinb = wsina*wsinb / 128
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word Axx = wcosa*wcosb / 128
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word Axy = (wcosa_sinb*wsinc - wsina*wcosc) / 128
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word Axz = (wcosa_sinb*wcosc + wsina*wsinc) / 128
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word Ayx = wsina*wcosb / 128
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word Ayy = (wsina_sinb*wsinc + wcosa*wcosc) / 128
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word Ayz = (wsina_sinb*wcosc - wcosa*wsinc) / 128
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word Azx = -wsinb
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word Azy = wcosb*wsinc / 128
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word Azz = wcosb*wcosc / 128
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ubyte @zp i
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for i in 0 to len(xcoor)-1 {
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; don't normalize by dividing by 128, instead keep some precision for perspective calc later
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rotatedx[i] = (Axx*xcoor[i] + Axy*ycoor[i] + Axz*zcoor[i])
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rotatedy[i] = (Ayx*xcoor[i] + Ayy*ycoor[i] + Ayz*zcoor[i])
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rotatedz[i] = (Azx*xcoor[i] + Azy*ycoor[i] + Azz*zcoor[i])
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}
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}
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sub draw_lines() {
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ubyte @zp i
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for i in len(edgesFrom) -1 downto 0 {
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ubyte @zp vFrom = edgesFrom[i]
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ubyte @zp vTo = edgesTo[i]
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word @zp persp1 = 256 + rotatedz[vFrom]/256
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word @zp persp2 = 256 + rotatedz[vTo]/256
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graphics.line(rotatedx[vFrom] / persp1 + graphics.WIDTH/2 as uword,
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rotatedy[vFrom] / persp1 + graphics.HEIGHT/2 as ubyte,
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rotatedx[vTo] / persp2 + graphics.WIDTH/2 as uword,
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rotatedy[vTo] / persp2 + graphics.HEIGHT/2 as ubyte)
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}
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}
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}
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