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openglvectorglslscalar

GLSL sum of vector vec3 and float

This may be odd because as I understand a vector and a scalar cannot be added. However I've found this sample and in line 157 it doing the following operation:

hsv.x + vec3(0.,2./3.,1./3.)

where hsv.x happens to be a float number, the value comes from the mouse X coordinates and well the rest is a vec3.

My question is what is the result of that operation?

Solution

  • If you add a scalar to a vector, then the scalar will be add to each component of the vector, because the The OpenGL Shading Language specification (Version 4.6, Chapter 5 Operators and Expressions) says:

    One operand is a scalar, and the other is a vector or matrix. In this case, the scalar operation is applied independently to each component of the vector or matrix, resulting in the same size vector or matrix.