During the conversion of shaders written in Cg\/HLSL<\/b>, we often find the saturate()<\/b> function. This function is not valid in GLSL<\/b> even though on NVIDIA, the GLSL compiler accepts it (do not forget that NVIDIA’s GLSL compiler is based on Cg compiler). But ATI’s GLSL compiler will reject saturate() with a nice error. This function allows to limit the value of a variable to the range [0.0 – 1.0]. In GLSL, there is a simple manner to do the same thing: clamp()<\/b>.<\/p>\n
Cg code:<\/p>\n
\r\nfloat3 result = saturate(texCol0.rgb - Density*(texCol1.rgb));\r\n<\/pre>\nGLSL equivalent:<\/p>\n
\r\nvec3 result = clamp(texCol0.rgb - Density*(texCol1.rgb), 0.0, 1.0);\r\n<\/pre>\nBTW, don’t forget all float4, float3 and float2 which correct syntax in GLSL is vec4, vec3 and vec2.<\/p>\n
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Lors de la conversion de shaders \u00e9crits en Cg\/HLSL<\/b>, on trouve souvent la fonction saturate()<\/b>. Cette fonction n’est pas valide en GLSL<\/b> bien que sur les NVIDIA le compilateur l’accepte (n’oublions pas que le compilateur GLSL de NVIDIA repose sur le compilateur Cg). Mais le compilateur GLSL d’ATI g\u00e9n\u00e9rera une belle erreur \u00e0 la vue de saturate(). Cette fonction sert \u00e0 limit\u00e9 la valeur d’une variable entre 0.0 et 1.0. En GLSL il y un moyen tout simple de faire la m\u00eame chose: clamp()<\/b>.<\/p>\n
Code Cg:<\/p>\n
\r\nfloat3 result = saturate(texCol0.rgb - Density*(texCol1.rgb));\r\n<\/pre>\nEquivalent GLSL:<\/p>\n
\r\nvec3 result = clamp(texCol0.rgb - Density*(texCol1.rgb), 0.0, 1.0);\r\n<\/pre>\nAu passage lors des conversions, n’oubliez pas les float4, float3 et float2 qui s’\u00e9crivent en GLSL en vec4, vec3 et vec2.<\/p>\n","protected":false},"excerpt":{"rendered":"
During the conversion of shaders written in Cg\/HLSL, we often find the saturate() function. This function is not valid in GLSL even though on NVIDIA, the GLSL compiler accepts it (do not forget that NVIDIA’s GLSL compiler is based on Cg compiler). But ATI’s GLSL compiler will reject saturate() with a nice error. This function allows to limit the value of a variable to the … Continue reading Saturate function in GLSL<\/span>