unelaborated webgl2 feature in the docs about webgl2-fundamentals HOT 3 CLOSED

It depends on what you're trying to do. For example if you're trying to generate a histogram or do some GPGPU thing then you probably want pixel coords

The feature is in GLSL using the texelFetch function. You give a sampler, integer pixel coordinates and a mip level

  vec4 color = texelFetch(someUniformSampler, ivec2(pixelX, pixelY), intMipLevel);

from webgl2-fundamentals.

If you consider textures to be 2D arrays (or 3D arrays for 3D textures) then texelFetch lets you specifically address a single array element where that element contains up to 4 values (vec4, ivec4, uvec4, etc...). You can use texelFetch in either the vertex or fragment shaders.

The only sample on the site that uses texelFetch at the moment is the skinning article

It makes an array of 4 by N matrices in a texture and uses texelFetch to retrieve a matrix based on the index of the bone/joint for that matrix. You can compare it to the WebGL1 skinning article. WebGL1 doesn't have texelFetch so there's a whole section saying how to compute normalized texture coordinates to achieve something similar.

Sorry but there's no really GPGPU articles yet.

You're correct that for the fragment shader the GPU is destination based. It figures out which pixels it needs to draw and then executes the fragment shader asking what color it should make that pixel.

from webgl2-fundamentals.

Thanks greggman, you helped me alot)

from webgl2-fundamentals.