52 lines
1.2 KiB
GLSL
52 lines
1.2 KiB
GLSL
uniform sampler2D tex;
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uniform vec2 texsize;
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uniform int notex;
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out vec4 FragColor;
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float miplevel(in vec2 texture_coordinate)
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{
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// The OpenGL Graphics System: A Specification 4.2
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// - chapter 3.9.11, equation 3.21
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vec2 dx_vtc = dFdx(texture_coordinate);
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vec2 dy_vtc = dFdy(texture_coordinate);
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float delta_max_sqr = max(dot(dx_vtc, dx_vtc), dot(dy_vtc, dy_vtc));
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return 0.5 * log2(delta_max_sqr); // == log2(sqrt(delta_max_sqr));
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}
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void main() {
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if (notex != 0) {
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FragColor = gl_Color;
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return;
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}
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// Buggy Intel windows driver workaround
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vec4 levels[6] = vec4[](
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vec4(0.0, 0.0, 1.0, 0.8),
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vec4(0.0, 0.5, 1.0, 0.4),
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vec4(1.0, 1.0, 1.0, 0.0),
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vec4(1.0, 0.7, 0.0, 0.2),
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vec4(1.0, 0.3, 0.0, 0.6),
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vec4(1.0, 0.0, 0.0, 0.8)
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);
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float mip = miplevel(texsize * gl_TexCoord[0].xy) + 2.0;
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mip = clamp(mip, 0.0, 5.0);
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int lowmip = int(mip);
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int highmip = lowmip + 1;
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if (highmip > 5)
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highmip = 5;
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float mixer = fract(mip);
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vec4 mixcol = mix(levels[lowmip], levels[highmip], mixer);
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vec4 tcol = texture(tex, gl_TexCoord[0].xy);
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vec3 col = mix(tcol.xyz, mixcol.xyz, mixcol.a);
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FragColor = vec4(col, tcol.a);
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}
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