64 lines
2.6 KiB
GLSL
64 lines
2.6 KiB
GLSL
//------------------------------------------------------------------------------
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// Fog
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//------------------------------------------------------------------------------
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vec4 fog(vec4 color, vec3 view) {
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if (frameUniforms.fogDensity > 0.0) {
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float A = frameUniforms.fogDensity;
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float B = frameUniforms.fogHeightFalloff;
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float d = length(view);
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float h = view.y;
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// The function below is continuous at h=0, so to avoid a divide-by-zero, we use the
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// constant approximation 'B'. A better approximation would be B * (1 - 0.5 * B * h)
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float fogIntegralFunctionOfDistance = A * ((abs(h) < 0.001) ? B : ((1.0 - exp(-B * h)) / h));
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float fogIntegral = fogIntegralFunctionOfDistance * max(d - frameUniforms.fogStart, 0.0);
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float fogOpacity = max(1.0 - exp2(-fogIntegral), 0.0);
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// don't go above requested max opacity
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fogOpacity = min(fogOpacity, frameUniforms.fogMaxOpacity);
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// compute fog color
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vec3 fogColor = frameUniforms.fogColor;
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if (frameUniforms.fogColorFromIbl > 0.0) {
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// get fog color from envmap
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float lod = frameUniforms.iblRoughnessOneLevel;
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fogColor *= textureLod(light_iblSpecular, view, lod).rgb * frameUniforms.iblLuminance;
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}
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fogColor *= fogOpacity;
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if (frameUniforms.fogInscatteringSize >= 0.0) {
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// compute a new line-integral for a different start distance
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float inscatteringIntegral = fogIntegralFunctionOfDistance *
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max(d - frameUniforms.fogInscatteringStart, 0.0);
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float inscatteringOpacity = max(1.0 - exp2(-inscatteringIntegral), 0.0);
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// Add sun colored fog when looking towards the sun
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vec3 sunColor = frameUniforms.lightColorIntensity.rgb * frameUniforms.lightColorIntensity.w;
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float sunAmount = max(dot(view, frameUniforms.lightDirection) / d, 0.0); // between 0 and 1
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float sunInscattering = pow(sunAmount, frameUniforms.fogInscatteringSize);
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fogColor += sunColor * (sunInscattering * inscatteringOpacity);
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}
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#if defined(BLEND_MODE_OPAQUE)
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// nothing to do here
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#elif defined(BLEND_MODE_TRANSPARENT)
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fogColor *= color.a;
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#elif defined(BLEND_MODE_ADD)
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fogColor = vec3(0.0);
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#elif defined(BLEND_MODE_MASKED)
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// nothing to do here
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#elif defined(BLEND_MODE_MULTIPLY)
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// FIXME: unclear what to do here
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#elif defined(BLEND_MODE_SCREEN)
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// FIXME: unclear what to do here
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#endif
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color.rgb = color.rgb * (1.0 - fogOpacity) + fogColor;
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}
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return color;
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}
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