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https://github.com/irmen/prog8.git
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115 lines
3.3 KiB
Lua
115 lines
3.3 KiB
Lua
%import textio
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%import syslib
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%zeropage basicsafe
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; Note: this program can be compiled for multiple target systems.
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main {
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sub start() {
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txt.print("rectangles\nand circle\ndrawing.\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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txt.print("enter for disc:")
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void cbm.CHRIN()
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txt.nl()
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txt.clear_screen()
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disc(20, 12, 12)
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txt.print("enter for rectangles:")
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void cbm.CHRIN()
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txt.nl()
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txt.clear_screen()
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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, bool 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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txt.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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txt.setcc(x, y1, 42, 8)
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txt.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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txt.setcc(x1, y, 42, 7)
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txt.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 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 as byte
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while x>=y {
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txt.setcc(xcenter + x, ycenter + y, 81, 1)
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txt.setcc(xcenter - x, ycenter + y, 81, 2)
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txt.setcc(xcenter + x, ycenter - y, 81, 3)
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txt.setcc(xcenter - x, ycenter - y, 81, 4)
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txt.setcc(xcenter + y, ycenter + x, 81, 5)
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txt.setcc(xcenter - y, ycenter + x, 81, 6)
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txt.setcc(xcenter + y, ycenter - x, 81, 7)
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txt.setcc(xcenter - y, ycenter - x, 81, 8)
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y++
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if decisionOver2>=0 {
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x--
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decisionOver2 -= 2*x
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}
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decisionOver2 += 2*y
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decisionOver2++
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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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; NOTE: because of the symmetry drawing, some horizontal spans will be drawn multiple times.
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; because this is only a very low res (text tiles) disc, it's not worth optimizing that.
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ubyte x = radius
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ubyte y = 0
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byte decisionOver2 = 1-x as byte
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ubyte xx
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while x>=y {
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xx = cx-x
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repeat 2*x+1 {
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txt.setcc(xx, cy + y, 81, 11)
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txt.setcc(xx, cy - y, 81, 12)
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xx++
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}
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xx = cx-y
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repeat 2*y+1 {
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txt.setcc(xx, cy + x, 81, 13)
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txt.setcc(xx, cy - x, 81, 14)
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xx++
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}
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y++
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if decisionOver2>=0 {
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x--
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decisionOver2 -= 2*x
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}
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decisionOver2 += 2*y
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decisionOver2++
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}
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}
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}
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}
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