prog8/examples/cube3d.p8

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%import c64utils
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~ main {
const uword width = 40
const uword height = 25
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; vertices
byte[8] xcoor = [ -40, -40, -40, -40, 40, 40, 40, 40 ]
byte[8] ycoor = [ -40, -40, 40, 40, -40, -40, 40, 40 ]
byte[8] zcoor = [ -40, 40, -40, 40, -40, 40, -40, 40 ]
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; storage for rotated coordinates
word[len(xcoor)] rotatedx
word[len(ycoor)] rotatedy
word[len(zcoor)] rotatedz
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sub start() {
uword anglex
uword angley
uword anglez
word rz=33
word persp = (rz+200)
persp = rz / 25
persp = rz / height
persp = (rz+200) / height
while(true) {
rotate_vertices(msb(anglex), msb(angley), msb(anglez))
c64scr.clear_screenchars(32)
draw_edges()
anglex+=1000
angley+=433
anglez+=907
c64.PLOT(0,0,0)
c64scr.print("3d cube! (integer) ")
c64scr.print_ub(c64.TIME_LO)
c64scr.print(" jiffies/frame")
c64.TIME_LO=0
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}
}
sub rotate_vertices(ubyte ax, ubyte ay, ubyte az) {
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; rotate around origin (0,0,0)
; set up the 3d rotation matrix values
word wcosa = cos8(ax) as word
word wsina = sin8(ax) as word
word wcosb = cos8(ay) as word
word wsinb = sin8(ay) as word
word wcosc = cos8(az) as word
word wsinc = sin8(az) as word
word wcosa_sinb = wcosa*wsinb / 128
word wsina_sinb = wsina*wsinb / 128
word Axx = wcosa*wcosb / 128
word Axy = (wcosa_sinb*wsinc - wsina*wcosc) / 128
word Axz = (wcosa_sinb*wcosc + wsina*wsinc) / 128
word Ayx = wsina*wcosb / 128
word Ayy = (wsina_sinb*wsinc + wcosa*wcosc) / 128
word Ayz = (wsina_sinb*wcosc - wcosa*wsinc) / 128
word Azx = -wsinb
word Azy = wcosb*wsinc / 128
word Azz = wcosb*wcosc / 128
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for ubyte i in 0 to len(xcoor)-1 {
rotatedx[i] = (Axx*xcoor[i] + Axy*ycoor[i] + Axz*zcoor[i]) / 128
rotatedy[i] =(Ayx*xcoor[i] + Ayy*ycoor[i] + Ayz*zcoor[i]) / 128
rotatedz[i] = (Azx*xcoor[i] + Azy*ycoor[i] + Azz*zcoor[i]) / 128
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}
}
sub draw_edges() {
; plot the points of the 3d cube
; first the points on the back, then the points on the front (painter algorithm)
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for ubyte i in 0 to len(xcoor)-1 {
word rz = rotatedz[i]
if rz >= 10 {
word persp = (rz+200) / height
byte sx = rotatedx[i] / persp as byte + width/2
byte sy = rotatedy[i] / persp as byte + height/2
c64scr.setcc(sx as ubyte, sy as ubyte, 46, i+2)
}
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}
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for ubyte i in 0 to len(xcoor)-1 {
word rz = rotatedz[i]
if rz < 10 {
word persp = (rz+200) / height
byte sx = rotatedx[i] / persp as byte + width/2
byte sy = rotatedy[i] / persp as byte + height/2
c64scr.setcc(sx as ubyte, sy as ubyte, 81, i+2)
}
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}
}
}