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How to create GLSL arrays of uniforms in OpenGL?
According to http://www.opengl.org/wiki/Uniform_Buffer_Object, “Switching between uniform buffer bindings is typically faster than switching dozens of uniforms in a program”. If you have large numbers of lights and parameters, you could also send the data as float buffers.
How to use uniform int as index of const array?
I have a const array that define a few materials for directionnal light. I’d like to change the material using an uniform int as index of that array. Doing that leads to severe framerate drop.
How to pass weights in an array in OpenGL?
If you have seven materials, how about passing an array of seven floats, each defining a weight for each material, and mixing them instead using only one 1 and six 0s. Or in pseudocode, instead of doing this: If you want to use say, material 2, then you pass weights as {0, 0, 1, 0, 0, 0, 0}.
Why does uniform int not lead to framerate drop?
I’d like to change the material using an uniform int as index of that array. Doing that leads to severe framerate drop. I know that this could be fixed by just keeping the array in the cpu and send the material as uniform. But why does this not lead to framerate drop and the other do?
Where can I find uniform variables in GLSL?
The application feeds these variables to the graphics pipeline and they are accessible in all stages of the pipeline, i.e. any shader can access every uniform variable, as long as it declares the variable. These variables are read only, as far as shaders are concerned. Uniforms can be grouped in blocks, or defined individually.
How to create a dynamic array in GLSL?
In your case you should define the array as the maximum number of lights you will process and then use a uniform to control the number of iterations you do on this array. On the CPU side you can set a subset of the lights [] array according to the ‘size’ variable.
How to set lights array according to size?
On the CPU side you can set a subset of the lights [] array according to the ‘size’ variable. I think (speculate) the likely reason for this is that it would be impossible to determine the location of a uniform if there are variable sized arrays in your uniform list which depend on the value of another uniform.. e.g.
How to get index of uniform block in OpenGL?
First, we get the index of the uniform block by calling glGetUniformBlockIndex, then we query for the size of the block by calling glGetActiveUniformBlockiv. After getting the size, we allocate a temporary buffer named blockBuffer to hold the data for our block.
How to use uniform Buffer objects in OpenGL?
Since the layout of the data within a uniform buffer object is implementation dependent, it required us to query for the variable offsets. However, one can avoid this by asking OpenGL to use the standard layout std140. This is accomplished by using a layout qualifier when declaring the uniform block.
Which is the std140 layout for OpenGL?
The std140 layout is described in detail within the OpenGL specification document (available at http://www.opengl.org ). Other options for the layout qualifier that apply to uniform block layouts include packed and shared.