6d2c2aecff
There are two main reasons to desire an OpenGL 2 renderer:
1. Compatibility. The compatibility profile, ironically, does not
offer a lot of compatibility, and our OpenGL 1 renderer will not
run on Android, iOS, or WebGL.
2. Performance. The immediate mode does not scale, and in fact
becomes very slow with only a moderate amount of lines on screen,
and only a somewhat large amount of triangles.
This commit implements a basic OpenGL 2 renderer that uses only
features from the (OpenGL 3.2) core profile. It is not yet faster
than the OpenGL 1 renderer, primarily because it uses a lot of small
draw calls.
This commit uses OpenGL 2 on Linux and Mac OS X directly (i.e. links
to the GL symbols from version 2+); on Windows this is impossible
with the default drivers, so for now OpenGL 1 is still used there.
38 lines
1.0 KiB
GLSL
38 lines
1.0 KiB
GLSL
//-----------------------------------------------------------------------------
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// SolveSpace Edge rendering shader
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//
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// Copyright 2016 Aleksey Egorov
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//-----------------------------------------------------------------------------
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#version 120
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const float feather = 0.5;
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uniform vec4 color;
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uniform float pixel;
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uniform float width;
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uniform float patternLen;
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uniform float patternScale;
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uniform sampler2D pattern;
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varying vec3 fragLoc;
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void main() {
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// lookup distance texture
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vec4 v = texture2D(pattern, vec2(fragLoc.z / patternScale, 0.0));
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// decode distance value
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float val = dot(v, vec4(1.0, 1.0 / 255.0, 1.0 / 65025.0, 1.0 / 160581375.0));
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// calculate cap
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float dist = length(vec2(val * patternScale / (patternLen * width) + abs(fragLoc.x), fragLoc.y));
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// perform antialising
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float k = smoothstep(1.0 - 2.0 * feather * pixel / (width + feather * pixel), 1.0, abs(dist));
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// perfrom alpha-test
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if(k == 1.0) discard;
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// write resulting color
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gl_FragColor = vec4(color.rgb, color.a * (1.0 - k));
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}
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