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.
41 lines
1.1 KiB
GLSL
41 lines
1.1 KiB
GLSL
//-----------------------------------------------------------------------------
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// SolveSpace Point 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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attribute vec3 pos;
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attribute vec2 loc;
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uniform mat4 modelview;
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uniform mat4 projection;
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uniform float width;
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uniform float pixel;
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varying vec2 fragLoc;
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void main() {
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// get camera vectors from modelview matrix
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vec3 u = vec3(modelview[0].x, modelview[1].x, modelview[2].x);
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vec3 v = vec3(modelview[0].y, modelview[1].y, modelview[2].y);
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// calculate point contour extension basis for constant width and caps
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// calculate point extension width considering antialiasing
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float ext = width + feather * pixel;
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// extend point contour
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vec3 vertex = pos;
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vertex += ext * loc.x * normalize(u);
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vertex += ext * loc.y * normalize(v);
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// write fragment location for calculating caps and antialiasing
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fragLoc = loc;
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// transform resulting vertex with modelview and projection matrices
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gl_Position = projection * modelview * vec4(vertex, 1.0);
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}
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