51 lines
1.5 KiB
GLSL
51 lines
1.5 KiB
GLSL
uniform sampler2D baseTexture;
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uniform sampler2D normalTexture;
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uniform sampler2D textureFlags;
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uniform vec4 skyBgColor;
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uniform float fogDistance;
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uniform vec3 eyePosition;
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varying mediump vec4 varColor;
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varying mediump vec2 varTexCoord;
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varying mediump vec3 eyeVec;
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bool normalTexturePresent = false;
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bool texTileableHorizontal = false;
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bool texTileableVertical = false;
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bool texSeamless = false;
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const float e = 2.718281828459;
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const float BS = 10.0;
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const float fogStart = FOG_START;
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const float fogShadingParameter = 1.0 / (1.0 - fogStart);
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void main(void)
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{
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vec2 uv = varTexCoord.st;
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vec4 base = texture2D(baseTexture, uv).rgba;
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#ifdef USE_DISCARD
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if (base.a == 0.0)
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discard;
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#endif
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vec4 col = base;
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col *= varColor;
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// Due to a bug in some (older ?) graphics stacks (possibly in the glsl compiler ?),
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// the fog will only be rendered correctly if the last operation before the
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// clamp() is an addition. Else, the clamp() seems to be ignored.
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// E.g. the following won't work:
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// float clarity = clamp(fogShadingParameter
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// * (fogDistance - length(eyeVec)) / fogDistance), 0.0, 1.0);
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// As additions usually come for free following a multiplication, the new formula
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// should be more efficient as well.
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// Note: clarity = (1 - fogginess)
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if (fogDistance > 0.0) { // -1.0 means disabled
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float clarity = clamp(fogShadingParameter
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- fogShadingParameter * length(eyeVec) / fogDistance, 0.0, 1.0);
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col = mix(skyBgColor, col, clarity);
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}
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gl_FragColor = vec4(col.rgb, base.a);
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}
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