Xiaolin Wu's line algorithm: Difference between revisions
Content added Content deleted
(→{{header|J}}: use isidraw in j802) |
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const |
const |
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FPS=1000 div 60; |
FPS = 1000 div 60; |
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SCALE=6; |
SCALE = 6; |
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var |
var |
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origin: TSDL_Point; |
origin: TSDL_Point; |
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event: TSDL_Event; |
event: TSDL_Event; |
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line_alpha: byte=255; |
line_alpha: byte = 255; |
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procedure SDL_RenderDrawWuLine(renderer: PSDL_Renderer; x1, y1, x2, y2: longint); |
procedure SDL_RenderDrawWuLine(renderer: PSDL_Renderer; x1, y1, x2, y2: longint); |
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tmp: longint; |
tmp: longint; |
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begin |
begin |
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tmp:=a; |
tmp := a; |
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a:=b; |
a := b; |
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b:=tmp; |
b := tmp; |
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end; |
end; |
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begin |
begin |
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if a=0 then |
if a = 0 then |
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exit; |
exit; |
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SDL_GetRenderDrawColor(renderer, @r, @g, @b, @a); |
SDL_GetRenderDrawColor(renderer, @r, @g, @b, @a); |
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if abs(y2-y1)>abs(x2-x1) then |
if abs(y2 - y1) > abs(x2 - x1) then |
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begin |
begin |
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swap(x1, y1); |
swap(x1, y1); |
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swap(x2, y2); |
swap(x2, y2); |
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px:=@y; |
px := @y; |
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py:=@x; |
py := @x; |
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end |
end |
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else |
else |
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begin |
begin |
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px:=@x; |
px := @x; |
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py:=@y; |
py := @y; |
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end; |
end; |
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if x1>x2 then |
if x1 > x2 then |
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begin |
begin |
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swap(x1, x2); |
swap(x1, x2); |
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swap(y1, y2); |
swap(y1, y2); |
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end; |
end; |
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x:=x2-x1; |
x := x2 - x1; |
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if x=0 then |
if x = 0 then |
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x:=1; |
x := 1; |
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gradient:=(y2-y1)/x; |
gradient := (y2 - y1) / x; |
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iy:=y1; |
iy := y1; |
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for x:=x1 to x2 do |
for x := x1 to x2 do |
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begin |
begin |
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a_new:=round(a*frac(iy)); |
a_new := round(a * frac(iy)); |
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y:=floor(iy); |
y := floor(iy); |
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SDL_SetRenderDrawColor(renderer, r, g, b, a-a_new); |
SDL_SetRenderDrawColor(renderer, r, g, b, a-a_new); |
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SDL_RenderDrawPoint(renderer, px^, py^); |
SDL_RenderDrawPoint(renderer, px^, py^); |
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SDL_SetRenderDrawColor(renderer, r, g, b, a_new); |
SDL_SetRenderDrawColor(renderer, r, g, b, a_new); |
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SDL_RenderDrawPoint(renderer, px^, py^); |
SDL_RenderDrawPoint(renderer, px^, py^); |
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iy:=iy+gradient; |
iy := iy + gradient; |
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end; |
end; |
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SDL_SetRenderDrawColor(renderer, r, g, b, a); |
SDL_SetRenderDrawColor(renderer, r, g, b, a); |
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begin |
begin |
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SDL_Init(SDL_INIT_VIDEO); |
SDL_Init(SDL_INIT_VIDEO); |
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win:=SDL_CreateWindow('Xiaolin Wu''s line algorithm', SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, |
win := SDL_CreateWindow('Xiaolin Wu''s line algorithm', SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, |
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640, 480, SDL_WINDOW_RESIZABLE); |
640, 480, SDL_WINDOW_RESIZABLE); |
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ren:=SDL_CreateRenderer(win, -1, 0); |
ren := SDL_CreateRenderer(win, -1, 0); |
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if ren=NIL then |
if ren = NIL then |
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begin |
begin |
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writeln(SDL_GetError); |
writeln(SDL_GetError); |
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SDL_SetCursor(SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_CROSSHAIR)); |
SDL_SetCursor(SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_CROSSHAIR)); |
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mouse_x:=0; |
mouse_x := 0; |
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mouse_y:=0; |
mouse_y := 0; |
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origin.x:=0; |
origin.x := 0; |
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origin.y:=0; |
origin.y := 0; |
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repeat |
repeat |
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while SDL_PollEvent(@event)=1 do |
while SDL_PollEvent(@event) = 1 do |
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case event.type_ of |
case event.type_ of |
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SDL_KEYDOWN: |
SDL_KEYDOWN: |
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if event.key.keysym.sym=SDLK_ESCAPE then |
if event.key.keysym.sym = SDLK_ESCAPE then |
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halt; |
halt; |
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SDL_MOUSEBUTTONDOWN: |
SDL_MOUSEBUTTONDOWN: |
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begin |
begin |
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origin.x:=mouse_x; |
origin.x := mouse_x; |
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origin.y:=mouse_y; |
origin.y := mouse_y; |
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end; |
end; |
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SDL_MOUSEMOTION: |
SDL_MOUSEMOTION: |
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with event.motion do |
with event.motion do |
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begin |
begin |
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mouse_x:=x div SCALE; |
mouse_x := x div SCALE; |
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mouse_y:=y div SCALE; |
mouse_y := y div SCALE; |
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end; |
end; |
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SDL_MOUSEWHEEL: |
SDL_MOUSEWHEEL: |
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line_alpha:=EnsureRange(line_alpha+event.wheel.y*20, 0, 255); |
line_alpha := EnsureRange(line_alpha + event.wheel.y * 20, 0, 255); |
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SDL_QUITEV: |
SDL_QUITEV: |
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halt; |
halt; |
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