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Fix unexplained shader issue (glsl compiler bug??) (#4757)
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Rogier-5 authored and Zeno- committed Nov 16, 2016
1 parent 8e61c1d commit 5f0dc8e78ad7e62959786efd5c7f72044aacb53a
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Showing 3 changed files with 42 additions and 6 deletions.
@@ -19,6 +19,8 @@ bool normalTexturePresent = false;

const float e = 2.718281828459;
const float BS = 10.0;
const float fogStart = 0.4;
const float fogShadingParameter = 1 / ( 1 - fogStart);

#ifdef ENABLE_TONE_MAPPING

@@ -199,8 +201,18 @@ void main(void)
#endif

if (fogDistance != 0.0) {
float d = clamp((fogDistance - length(eyeVec)) / (fogDistance * 0.6), 0.0, 1.0);
col = mix(skyBgColor, col, d);
// Due to a bug in some (older ?) graphics stacks (possibly in the glsl compiler ?),
// the fog will only be rendered correctly if the last operation before the
// clamp() is an addition. Else, the clamp() seems to be ignored.
// E.g. the following won't work:
// float clarity = clamp(fogShadingParameter
// * (fogDistance - length(eyeVec)) / fogDistance), 0.0, 1.0);
// As additions usually come for free following a multiplication, the new formula
// should be more efficient as well.
// Note: clarity = (1 - fogginess)
float clarity = clamp(fogShadingParameter
- fogShadingParameter * length(eyeVec) / fogDistance, 0.0, 1.0);
col = mix(skyBgColor, col, clarity);
}
col = vec4(col.rgb, base.a);

@@ -21,6 +21,8 @@ bool texSeamless = false;

const float e = 2.718281828459;
const float BS = 10.0;
const float fogStart = 0.4;
const float fogShadingParameter = 1 / ( 1 - fogStart);

#ifdef ENABLE_TONE_MAPPING

@@ -155,8 +157,18 @@ vec4 base = texture2D(baseTexture, uv).rgba;
#endif

if (fogDistance != 0.0) {
float d = clamp((fogDistance - length(eyeVec)) / (fogDistance * 0.6), 0.0, 1.0);
col = mix(skyBgColor, col, d);
// Due to a bug in some (older ?) graphics stacks (possibly in the glsl compiler ?),
// the fog will only be rendered correctly if the last operation before the
// clamp() is an addition. Else, the clamp() seems to be ignored.
// E.g. the following won't work:
// float clarity = clamp(fogShadingParameter
// * (fogDistance - length(eyeVec)) / fogDistance), 0.0, 1.0);
// As additions usually come for free following a multiplication, the new formula
// should be more efficient as well.
// Note: clarity = (1 - fogginess)
float clarity = clamp(fogShadingParameter
- fogShadingParameter * length(eyeVec) / fogDistance, 0.0, 1.0);
col = mix(skyBgColor, col, clarity);
}
col = vec4(col.rgb, base.a);

@@ -19,6 +19,8 @@ bool texSeamless = false;

const float e = 2.718281828459;
const float BS = 10.0;
const float fogStart = 0.4;
const float fogShadingParameter = 1 / ( 1 - fogStart);

void get_texture_flags()
{
@@ -107,8 +109,18 @@ void main(void)
vec4 col = vec4(color.rgb, base.a);
col *= gl_Color;
if (fogDistance != 0.0) {
float d = clamp((fogDistance - length(eyeVec)) / (fogDistance * 0.6), 0.0, 1.0);
col = mix(skyBgColor, col, d);
// Due to a bug in some (older ?) graphics stacks (possibly in the glsl compiler ?),
// the fog will only be rendered correctly if the last operation before the
// clamp() is an addition. Else, the clamp() seems to be ignored.
// E.g. the following won't work:
// float clarity = clamp(fogShadingParameter
// * (fogDistance - length(eyeVec)) / fogDistance), 0.0, 1.0);
// As additions usually come for free following a multiplication, the new formula
// should be more efficient as well.
// Note: clarity = (1 - fogginess)
float clarity = clamp(fogShadingParameter
- fogShadingParameter * length(eyeVec) / fogDistance, 0.0, 1.0);
col = mix(skyBgColor, col, clarity);
}
gl_FragColor = vec4(col.rgb, base.a);
}

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