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https://github.com/irmen/prog8.git
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94 lines
2.8 KiB
Lua
94 lines
2.8 KiB
Lua
%import c64lib
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%import c64utils
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%zeropage basicsafe
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main {
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sub start() {
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c64scr.print("mid-point\ncircle\n and\nbresenham\nline\nalgorithms.\n")
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const ubyte xcenter = 20
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const ubyte ycenter = 12
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ubyte r
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for r in 3 to 12 step 3 {
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circle(r)
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}
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line(5,3, 30,3)
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line(5,3, 5, 24)
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line(30,3,30,24)
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line(5,24,30,24)
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line(1, 10, 38, 24)
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line(1, 20, 38, 2)
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line(20, 4, 10, 24)
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line(39, 16, 12, 0)
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; TODO fix crash arg type incompatible c64scr.setcc(x0, y0 + radius, 81, 1)
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sub line(ubyte x1, ubyte y1, ubyte x2, ubyte y2) {
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byte d = 0
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ubyte dx = abs(x2 - x1)
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ubyte dy = abs(y2 - y1)
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ubyte dx2 = 2 * dx
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ubyte dy2 = 2 * dy
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byte ix = sgn(x2 as byte - x1 as byte)
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byte iy = sgn(y2 as byte - y1 as byte)
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ubyte x = x1
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ubyte y = y1
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if dx >= dy {
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; TODO fix assembler problem when defining label here
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forever {
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c64scr.setcc(x, y, 42, 5)
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if x==x2
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return
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x += ix
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d += dy2
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if d > dx {
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y += iy
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d -= dx2
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}
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}
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} else {
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; TODO fix assembler problem when defining label here
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forever {
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c64scr.setcc(x, y, 42, 5)
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if y == y2
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return
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y += iy
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d += dx2
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if d > dy {
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x += ix
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d -= dy2
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}
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}
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}
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}
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sub circle(ubyte radius) {
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byte x = radius as byte
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byte y = 0
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byte decisionOver2 = 1-x
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while x>=y {
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c64scr.setcc(xcenter + x as ubyte, ycenter + y as ubyte, 81, 1)
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c64scr.setcc(xcenter - x as ubyte, ycenter + y as ubyte, 81, 1)
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c64scr.setcc(xcenter + x as ubyte, ycenter - y as ubyte, 81, 1)
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c64scr.setcc(xcenter - x as ubyte, ycenter - y as ubyte, 81, 1)
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c64scr.setcc(xcenter + y as ubyte, ycenter + x as ubyte, 81, 1)
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c64scr.setcc(xcenter - y as ubyte, ycenter + x as ubyte, 81, 1)
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c64scr.setcc(xcenter + y as ubyte, ycenter - x as ubyte, 81, 1)
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c64scr.setcc(xcenter - y as ubyte, ycenter - x as ubyte, 81, 1)
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y++
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if decisionOver2<=0
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decisionOver2 += 2*y+1
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else {
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x--
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decisionOver2 += 2*(y-x)+1
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}
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}
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}
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}
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}
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