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https://github.com/ZDoom/gzdoom.git
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f710518903
Due to the way the engine works it needs to render a lot of small primitives with frequent state changes. But due to the performance of buffer uploads it is impossible to upload each primitive's vertices to a buffer separately because buffer uploads nearly always stall the GPU. On the other hand, in order to reduce the amount of buffer uploads all the necessary state changes would have to be saved in an array until they can finally be used. This method also imposed an unacceptable overhead. Fortunately, uploading uniform arrays is very fast and doesn't cause GPU stalls, so now the engine puts the vertex data per primitive into a uniform array and uses a static vertex buffer to index the array in the vertex shader. This method offers the same performance as immediate mode but only uses core profile features.
56 lines
1.4 KiB
Text
56 lines
1.4 KiB
Text
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in vec4 aVertex2;
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out vec4 pixelpos;
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out vec2 glowdist;
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#ifdef UNIFORM_VB
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uniform float fakeVB[100];
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#endif
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void main()
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{
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#ifdef UNIFORM_VB
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vec4 vert;
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vec4 tc;
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if (gl_MultiTexCoord0.x >= 100000.0)
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{
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int fakeVI = int(gl_MultiTexCoord0.y)*5;
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vert = gl_Vertex + vec4(fakeVB[fakeVI], fakeVB[fakeVI+1], fakeVB[fakeVI+2], 0.0);
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tc = vec4(fakeVB[fakeVI+3], fakeVB[fakeVI+4], 0.0, 0.0);
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}
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else
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{
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vert = gl_Vertex;
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tc = gl_MultiTexCoord0;
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}
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#else
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#define vert gl_Vertex
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#define tc gl_MultiTexCoord0
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#endif
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vec4 worldcoord = ModelMatrix * mix(vert, aVertex2, uInterpolationFactor);
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vec4 eyeCoordPos = ViewMatrix * worldcoord;
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gl_FrontColor = gl_Color;
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pixelpos.xyz = worldcoord.xyz;
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pixelpos.w = -eyeCoordPos.z/eyeCoordPos.w;
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glowdist.x = -((uGlowTopPlane.w + uGlowTopPlane.x * worldcoord.x + uGlowTopPlane.y * worldcoord.z) * uGlowTopPlane.z) - worldcoord.y;
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glowdist.y = worldcoord.y + ((uGlowBottomPlane.w + uGlowBottomPlane.x * worldcoord.x + uGlowBottomPlane.y * worldcoord.z) * uGlowBottomPlane.z);
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#ifdef SPHEREMAP
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vec3 u = normalize(eyeCoordPos.xyz);
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vec3 n = normalize(gl_NormalMatrix * gl_Normal);
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vec3 r = reflect(u, n);
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float m = 2.0 * sqrt( r.x*r.x + r.y*r.y + (r.z+1.0)*(r.z+1.0) );
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vec2 sst = vec2(r.x/m + 0.5, r.y/m + 0.5);
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gl_TexCoord[0].xy = sst;
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#else
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gl_TexCoord[0] = TextureMatrix * tc;
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#endif
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gl_Position = ProjectionMatrix * eyeCoordPos;
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}
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