mirror of
https://github.com/irmen/prog8.git
synced 2024-08-20 21:29:18 +00:00
165 lines
4.8 KiB
Lua
165 lines
4.8 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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ubyte r
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for r in 3 to 12 step 3 {
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circle(20, 12, r)
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}
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c64scr.print("enter for disc:")
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void c64.CHRIN()
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c64.CHROUT('\n')
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c64scr.clear_screen(' ', 1)
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disc(20, 12, 12)
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c64scr.print("enter for lines:")
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void c64.CHRIN()
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c64.CHROUT('\n')
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c64scr.clear_screen(' ', 1)
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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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c64scr.print("enter for rectangles:")
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void c64.CHRIN()
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c64.CHROUT('\n')
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c64scr.clear_screen(' ', 1)
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rect(4, 8, 37, 23, false)
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rect(20, 12, 30, 20, true)
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rect(10, 10, 10, 10, false)
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rect(6, 0, 16, 20, true)
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sub rect(ubyte x1, ubyte y1, ubyte x2, ubyte y2, ubyte fill) {
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ubyte x
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ubyte y
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if fill {
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for y in y1 to y2 {
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for x in x1 to x2 {
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c64scr.setcc(x, y, 42, x+y)
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}
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}
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} else {
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for x in x1 to x2 {
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c64scr.setcc(x, y1, 42, 8)
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c64scr.setcc(x, y2, 42, 8)
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}
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if y2>y1 {
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for y in y1+1 to y2-1 {
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c64scr.setcc(x1, y, 42, 7)
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c64scr.setcc(x2, y, 42, 7)
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}
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}
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}
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}
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sub line(ubyte x1, ubyte y1, ubyte x2, ubyte y2) {
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; Bresenham algorithm
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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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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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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 xcenter, ubyte ycenter, ubyte radius) {
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; Midpoint algorithm
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ubyte x = radius
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ubyte 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, ycenter + y as ubyte, 81, 1)
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c64scr.setcc(xcenter - x, ycenter + y as ubyte, 81, 2)
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c64scr.setcc(xcenter + x, ycenter - y as ubyte, 81, 3)
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c64scr.setcc(xcenter - x, ycenter - y as ubyte, 81, 4)
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c64scr.setcc(xcenter + y, ycenter + x as ubyte, 81, 5)
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c64scr.setcc(xcenter - y, ycenter + x as ubyte, 81, 6)
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c64scr.setcc(xcenter + y, ycenter - x as ubyte, 81, 7)
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c64scr.setcc(xcenter - y, ycenter - x as ubyte, 81, 8)
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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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sub disc(ubyte cx, ubyte cy, ubyte radius) {
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; Midpoint algorithm, filled
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ubyte x = radius
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ubyte y = 0
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byte decisionOver2 = 1-x
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ubyte xx
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while x>=y {
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for xx in cx to cx+x {
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c64scr.setcc(xx, cy + y as ubyte, 81, 1)
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c64scr.setcc(xx, cy - y as ubyte, 81, 2)
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}
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for xx in cx-x to cx-1 {
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c64scr.setcc(xx, cy + y as ubyte, 81, 3)
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c64scr.setcc(xx, cy - y as ubyte, 81, 4)
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}
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for xx in cx to cx+y {
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c64scr.setcc(xx, cy + x as ubyte, 81, 5)
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c64scr.setcc(xx, cy - x as ubyte, 81, 6)
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}
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for xx in cx-y to cx {
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c64scr.setcc(xx, cy + x as ubyte, 81, 7)
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c64scr.setcc(xx, cy - x as ubyte, 81, 8)
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}
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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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