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I'm working on porting our application from Windows to Linux and I need to understand what does operator [] do in HLSL and how to port in to GLSL.

I have code like this:

red = texture.Sample(sampler, uv)[x];

Sample function should return a pixel value, right? Is x a kind of offset?

Rabbid76
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Dmitry
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1 Answers1

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[]-operator is the array member selection operator and can also be used to access a vector.

The equivalent glsl code to 

red = texture.Sample(sampler, uv)[x];

is 

float red = texture(sampler, uv)[x];

texture returns a value of type vec4 (e.g. for sampler2D). The components of the vector can be accessed by the index operator. Since x is the index, it has to be a variable or constant with an integral data type. The vector has 4 components (.x, .y, .z, .w respectively .r, .g, .b, .a), so the value of x has to be 0, 1, 2 or 3.
texture(sampler, uv)[0] is the same as texture(sampler, uv).r. See also GLSL- Swizzling.

Rabbid76
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