Apple-2-SW/prog8
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prog8/examples/cx16/cobramk3-gfx.p8

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%target cx16
%import syslib
%import test_stack
%import conv
; TODO add all other Elite's ships, show their name, advance to next ship on keypress
main {
; storage for rotated coordinates
word[shipdata.totalNumberOfPoints] rotatedx
word[shipdata.totalNumberOfPoints] rotatedy
word[shipdata.totalNumberOfPoints] rotatedz
sub start() {
uword anglex
uword angley
uword anglez
void cx16.screen_set_mode($80)
cx16.GRAPH_init(0)
cx16.GRAPH_set_colors(13, 6, 6)
cx16.GRAPH_clear()
print_ship_name()
repeat {
rotate_vertices(msb(anglex), msb(angley), msb(anglez))
cx16.GRAPH_set_colors(0, 0, 0)
cx16.GRAPH_draw_rect(32, 10, 256, 185, 0, true)
cx16.GRAPH_set_colors(1, 0, 0)
draw_lines_hiddenremoval()
; draw_lines()
anglex += 217
angley -= 505
anglez += 452
; test_stack.test()
}
}
sub print_ship_name() {
cx16.r0 = 32
cx16.r1 = 8
ubyte c
for c in "ship: "
cx16.GRAPH_put_next_char(c)
for c in shipdata.shipName
cx16.GRAPH_put_next_char(c)
cx16.r0 += 16
print_number_gfx(shipdata.totalNumberOfPoints)
for c in " vertices, "
cx16.GRAPH_put_next_char(c)
print_number_gfx(shipdata.totalNumberOfEdges)
for c in " edges, "
cx16.GRAPH_put_next_char(c)
print_number_gfx(shipdata.totalNumberOfFaces)
for c in " faces"
cx16.GRAPH_put_next_char(c)
}
asmsub print_number_gfx(ubyte num @ A) clobbers(A,Y) {
%asm {{
phx
jsr conv.ubyte2decimal
phx
pha
cpy #'0'
beq +
tya
jsr cx16.GRAPH_put_char
pla
jsr cx16.GRAPH_put_char
jmp _ones
+ pla
cmp #'0'
beq _ones
jsr cx16.GRAPH_put_char
_ones pla
jsr cx16.GRAPH_put_char
plx
rts
}}
}
sub rotate_vertices(ubyte ax, ubyte ay, ubyte az) {
; rotate around origin (0,0,0)
; set up the 3d rotation matrix values
word wcosa = cos8(ax)
word wsina = sin8(ax)
word wcosb = cos8(ay)
word wsinb = sin8(ay)
word wcosc = cos8(az)
word wsinc = sin8(az)
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
ubyte @zp i
for i in 0 to shipdata.totalNumberOfPoints-1 {
; don't normalize by dividing by 128, instead keep some precision for perspective calc later
rotatedx[i] = Axx*shipdata.xcoor[i] + Axy*shipdata.ycoor[i] + Axz*shipdata.zcoor[i]
rotatedy[i] = Ayx*shipdata.xcoor[i] + Ayy*shipdata.ycoor[i] + Ayz*shipdata.zcoor[i]
rotatedz[i] = Azx*shipdata.xcoor[i] + Azy*shipdata.ycoor[i] + Azz*shipdata.zcoor[i]
}
}
const uword screen_width = 320
const ubyte screen_height = 200
sub draw_lines() {
; simple routine that draw all edges, exactly once, but no hidden line removal.
ubyte @zp i
for i in shipdata.totalNumberOfEdges -1 downto 0 {
ubyte @zp vFrom = shipdata.edgesFrom[i]
ubyte @zp vTo = shipdata.edgesTo[i]
word persp1 = 200 + rotatedz[vFrom]/256
word persp2 = 200 + rotatedz[vTo]/256
cx16.GRAPH_draw_line(rotatedx[vFrom] / persp1 + screen_width/2 as uword,
rotatedy[vFrom] / persp1 + screen_height/2 as uword,
rotatedx[vTo] / persp2 + screen_width/2 as uword,
rotatedy[vTo] / persp2 + screen_height/2 as uword)
}
}
sub draw_lines_hiddenremoval() {
; complex drawing routine that draws the ship model based on its faces,
; where it uses the surface normals to determine visibility.
memset(edgestodraw, shipdata.totalNumberOfEdges, true)
ubyte @zp edgeIdx = 0
ubyte @zp pointIdx = 0
ubyte faceNumber
for faceNumber in shipdata.totalNumberOfFaces -1 downto 0 {
if facing_away(pointIdx) {
; don't draw this face, fast-forward over the edges and points
edgeIdx += 3 ; every face hast at least 3 edges
while shipdata.facesEdges[edgeIdx]!=255 {
edgeIdx++
}
edgeIdx++
pointIdx += 3 ; every face has at least 3 points
while shipdata.facesPoints[pointIdx]!=255 {
pointIdx++
}
pointIdx++
} else {
; draw this face
ubyte @zp e1 = shipdata.facesEdges[edgeIdx]
edgeIdx ++
ubyte @zp e2 = shipdata.facesEdges[edgeIdx]
edgeIdx ++
ubyte @zp e3 = shipdata.facesEdges[edgeIdx]
edgeIdx ++
if edgestodraw[e1]
draw_edge(e1)
if edgestodraw[e2]
draw_edge(e2)
while e3!=255 {
if edgestodraw[e3]
draw_edge(e3)
e3 = shipdata.facesEdges[edgeIdx]
edgeIdx ++
}
; skip the rest of the facesPoints, we don't need them here anymore
pointIdx += 3 ; every face has at least 3 points
while shipdata.facesPoints[pointIdx]!=255 {
pointIdx++
}
pointIdx++
}
}
}
sub facing_away(ubyte edgePointsIdx) -> ubyte {
; simplistic visibility determination by checking the Z component of the surface normal
; TODO: actually take the line of sight vector into account
ubyte p1 = shipdata.facesPoints[edgePointsIdx]
edgePointsIdx++
ubyte p2 = shipdata.facesPoints[edgePointsIdx]
edgePointsIdx++
ubyte p3 = shipdata.facesPoints[edgePointsIdx]
word p1x = rotatedx[p1] / 128
word p1y = rotatedy[p1] / 128
word p2x = rotatedx[p2] / 128
word p2y = rotatedy[p2] / 128
word p3x = rotatedx[p3] / 128
word p3y = rotatedy[p3] / 128
return (p2x-p3x)*(p1y-p3y) - (p2y-p3y)*(p1x-p3x) > 0
}
ubyte[shipdata.totalNumberOfEdges] edgestodraw
sub draw_edge(ubyte edgeidx) {
edgestodraw[edgeidx] = false
ubyte vFrom = shipdata.edgesFrom[edgeidx]
ubyte vTo = shipdata.edgesTo[edgeidx]
word persp1 = 200 + rotatedz[vFrom]/256
word persp2 = 200 + rotatedz[vTo]/256
cx16.GRAPH_draw_line(rotatedx[vFrom] / persp1 + screen_width/2 as uword,
rotatedy[vFrom] / persp1 + screen_height/2 as uword,
rotatedx[vTo] / persp2 + screen_width/2 as uword,
rotatedy[vTo] / persp2 + screen_height/2 as uword)
}
}
shipdata {
; Ship model data converted from BBC Elite's Cobra MK 3
; downloaded from http://www.elitehomepage.org/archive/index.htm
const ubyte totalNumberOfEdges = 51
const ubyte totalNumberOfFaces = 22
const ubyte totalNumberOfPoints = 34
str shipName = "cobra-mk3"
; vertices
word[] xcoor = [ 32,-32,0,-120,120,-88,88,128,-128,0,-32,32,-36,-8,8,36,36,8,-8,-36,-1,-1,-80,-80,-88,80,88,80,1,1,1,1,-1,-1 ]
word[] ycoor = [ 0,0,26,-3,-3,16,16,-8,-8,26,-24,-24,8,12,12,8,-12,-16,-16,-12,-1,-1,-6,6,0,6,0,-6,-1,-1,1,1,1,1 ]
word[] zcoor = [ 76,76,24,-8,-8,-40,-40,-40,-40,-40,-40,-40,-40,-40,-40,-40,-40,-40,-40,-40,76,90,-40,-40,-40,-40,-40,-40,76,90,76,90,76,90 ]
; edges and faces
ubyte[] edgesFrom = [ 0,1,0,10,1,0,2,0,4,0,4,7,2,1,1,3,8,3,2,5,6,5,6,16,15,14,14,18,13,12,12,26,25,25,22,23,22,20,28,21,20,28,29,30,31,30,32,20,21,20,20 ]
ubyte[] edgesTo = [ 1,2,2,11,10,11,6,6,6,4,7,11,5,5,3,5,10,8,9,9,9,8,7,17,16,15,17,19,18,13,19,27,26,27,23,24,24,28,29,29,21,30,31,31,33,32,33,32,33,33,29 ]
ubyte[] facesPoints = [
0,1,2 ,255,
11,10,1,0 ,255,
0,2,6 ,255,
6,4,0 ,255,
4,7,11,0 ,255,
5,2,1 ,255,
1,3,5 ,255,
10,8,3,1 ,255,
9,2,5 ,255,
9,6,2 ,255,
3,8,5 ,255,
4,6,7 ,255,
5,8,10,11,7,6,9 ,255,
17,16,15,14 ,255,
19,18,13,12 ,255,
27,26,25 ,255,
22,23,24 ,255,
20,28,29,21 ,255,
30,28,29,31 ,255,
33,31,30,32 ,255,
20,32,33,21 ,255,
29,31,33,20 ,255
]
ubyte[] facesEdges = [
0,1,2 ,255,
3,4,0,5 ,255,
2,6,7 ,255,
8,9,7 ,255,
10,11,5,9 ,255,
12,1,13 ,255,
14,15,13 ,255,
16,17,14,4 ,255,
18,12,19 ,255,
20,6,18 ,255,
17,21,15 ,255,
8,22,10 ,255,
21,16,3,11,22,20,19 ,255,
23,24,25,26 ,255,
27,28,29,30 ,255,
31,32,33 ,255,
34,35,36 ,255,
37,38,39,40 ,255,
41,38,42,43 ,255,
44,43,45,46 ,255,
47,46,48,40 ,255,
42,44,49,50 ,255
]
}
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