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Make circle drawing more scalable #33

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Make circle drawing more scalable #33

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9f742e3
Make circle drawing more scalable
albinahlback Jan 14, 2021
e4e2f50
Add test to compare the drawing of old and new circle
albinahlback Jan 16, 2021
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67 changes: 21 additions & 46 deletions src/screen.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -159,54 +159,29 @@ end
sdl_colors(c::Colorant) = sdl_colors(convert(ARGB{Colors.FixedPointNumbers.Normed{UInt8,8}}, c))
sdl_colors(c::ARGB) = Int.(reinterpret.((red(c), green(c), blue(c), alpha(c))))

# improved circle drawing algorithm. slower but fills completely. needs optimization
function draw(s::Screen, circle::Circle, c::Colorant=colorant"black"; fill=false)
# define the center and needed sides of circle
centerX = Cint(circle.x)
centerY = Cint(circle.y)
int_rad = Cint(circle.r)
left = centerX - int_rad
top = centerY - int_rad

SDL2.SetRenderDrawColor(
s.renderer,
sdl_colors(c)...,
)

# we consider a grid with sides equal to the circle's diameter
for x in left:centerX
for y in top:centerY

# for each pixel in the top left quadrant of the grid we measure the distance from the center.
dist = sqrt( (centerX - x)^2 + (centerY - y)^2 )

# if it is close to the circle's radius it and all associated points in the other quadrants are colored in.
if (dist <= circle.r + 0.5 && dist >= circle.r - 0.5)
rel_x = centerX - x
rel_y = centerY - y

quad1 = (x , y )
quad2 = (centerX + rel_x, y )
quad3 = (x , centerY + rel_y)
quad4 = (quad2[1] , quad3[2] )

SDL2.RenderDrawPoint(s.renderer, quad1[1], quad1[2])
SDL2.RenderDrawPoint(s.renderer, quad2[1], quad2[2])
SDL2.RenderDrawPoint(s.renderer, quad3[1], quad3[2])
SDL2.RenderDrawPoint(s.renderer, quad4[1], quad4[2])

# if we are told to fill in the circle we draw lines between all of the quadrants to completely fill the circle
if (fill == true)
SDL2.RenderDrawLine(s.renderer, quad1[1], quad1[2], quad2[1], quad2[2])
SDL2.RenderDrawLine(s.renderer, quad2[1], quad2[2], quad4[1], quad4[2])
SDL2.RenderDrawLine(s.renderer, quad4[1], quad4[2], quad3[1], quad3[2])
SDL2.RenderDrawLine(s.renderer, quad3[1], quad3[2], quad1[1], quad1[2])
end
end

end
SDL2.SetRenderDrawColor(s.renderer, sdl_colors(c)...)
r = Cint(circle.r)
o = Cint.([circle.x; circle.y])

n = ceil(π * r / 2)
if fill
for j = 0:n
x = round(Cint, r * cos(j / n * π / 2))
y = round(Cint, r * sin(j / n * π / 2))
SDL2.RenderDrawLine(s.renderer, o[1] + x, o[2] + y, o[1] + x, o[2] - y)
SDL2.RenderDrawLine(s.renderer, o[1] - x, o[2] + y, o[1] - x, o[2] - y)
end

else
for j = 0:n
x = round(Cint, r * cos(j / n * π / 2))
y = round(Cint, r * sin(j / n * π / 2))
SDL2.RenderDrawPoint(s.renderer, o[1] + x, o[2] + y)
SDL2.RenderDrawPoint(s.renderer, o[1] - x, o[2] + y)
SDL2.RenderDrawPoint(s.renderer, o[1] + x, o[2] - y)
SDL2.RenderDrawPoint(s.renderer, o[1] - x, o[2] - y)
end
end
end

rect(x::Rect) = x
Expand Down
116 changes: 116 additions & 0 deletions test/circleperformance.jl
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Original file line number Diff line number Diff line change
@@ -0,0 +1,116 @@
# This files checks the new way to draw a circle versus the old way

using SimpleDirectMediaLayer
const SDL2 = SimpleDirectMediaLayer

circles = Vector{Int}[]
for j = 1:10
push!(circles, [10 + 4 * j; 50; j])
push!(circles, [100 + 30 * j; 500; 25 * j])
end

function newdraw(ren, circle; fill=false)
r = Cint(circle[3])
o = Cint.(circle[1:2])

n = ceil(π * r / 2)
if fill
for j = 0:n
x = round(Cint, r * cos(j / n * π / 2))
y = round(Cint, r * sin(j / n * π / 2))
SDL2.RenderDrawLine(ren, o[1] + x, o[2] + y, o[1] + x, o[2] - y)
SDL2.RenderDrawLine(ren, o[1] - x, o[2] + y, o[1] - x, o[2] - y)
end
else
for j = 0:n
x = round(Cint, r * cos(j / n * π / 2))
y = round(Cint, r * sin(j / n * π / 2))
SDL2.RenderDrawPoint(ren, o[1] + x, o[2] + y)
SDL2.RenderDrawPoint(ren, o[1] - x, o[2] + y)
SDL2.RenderDrawPoint(ren, o[1] + x, o[2] - y)
SDL2.RenderDrawPoint(ren, o[1] - x, o[2] - y)
end
end
end

function olddraw(ren, circle; fill=false)
# define the center and needed sides of circle
centerX = Cint(circle[1])
centerY = Cint(circle[2])
int_rad = Cint(circle[3])
left = centerX - int_rad
top = centerY - int_rad

# we consider a grid with sides equal to the circle's diameter
for x in left:centerX
for y in top:centerY

# for each pixel in the top left quadrant of the grid we measure the distance from the center.
dist = sqrt( (centerX - x)^2 + (centerY - y)^2 )

# if it is close to the circle's radius it and all associated points in the other quadrants are colored in.
if (dist <= int_rad + 0.5 && dist >= int_rad - 0.5)
rel_x = centerX - x
rel_y = centerY - y

quad1 = (x , y )
quad2 = (centerX + rel_x, y )
quad3 = (x , centerY + rel_y)
quad4 = (quad2[1] , quad3[2] )

SDL2.RenderDrawPoint(ren, quad1[1], quad1[2])
SDL2.RenderDrawPoint(ren, quad2[1], quad2[2])
SDL2.RenderDrawPoint(ren, quad3[1], quad3[2])
SDL2.RenderDrawPoint(ren, quad4[1], quad4[2])

# if we are told to fill in the circle we draw lines between all of the quadrants to completely fill the circle
if (fill == true)
SDL2.RenderDrawLine(ren, quad1[1], quad1[2], quad2[1], quad2[2])
SDL2.RenderDrawLine(ren, quad2[1], quad2[2], quad4[1], quad4[2])
SDL2.RenderDrawLine(ren, quad4[1], quad4[2], quad3[1], quad3[2])
SDL2.RenderDrawLine(ren, quad3[1], quad3[2], quad1[1], quad1[2])
end
end

end
end

end

function myinit()
SDL2.init()
win = SDL2.CreateWindow("",
Int32(0), Int32(0), Int32(800), Int32(600), UInt32(SDL2.WINDOW_SHOWN)
)

renderer = SDL2.CreateRenderer(win,
Int32(-1),
UInt32(SDL2.RENDERER_ACCELERATED | SDL2.RENDERER_PRESENTVSYNC)
)

SDL2.SetRenderDrawColor(renderer, 0, 0, 0, 255)
return renderer
end


function testold(renderer, circles, N, boolfill)
SDL2.SetRenderDrawColor(renderer, 255, 255, 255, 255)
for j = 1:N
SDL2.RenderClear(renderer)
for k = 1:length(circles)
olddraw(renderer, circles[k], fill=boolfill)
end
end
SDL2.Quit()
end

function testnew(renderer, circles, N, boolfill)
SDL2.SetRenderDrawColor(renderer, 255, 255, 255, 255)
for j = 1:N
SDL2.RenderClear(renderer)
for k = 1:length(circles)
newdraw(renderer, circles[k], fill=boolfill)
end
end
SDL2.Quit()
end