MathuSum Mut MathuSum Mut - 10 months ago 74
C++ Question

Interpolate data buffers using OpenGL?

I am writing an application that loads the vertices of two meshes (which serve as keyframes) into two separate OpenGL float data buffers. The two meshes have the same number of vertices.

I would like to compute intermediary frames by using linear interpolation between these two buffers (where I can specify the interpolation weighting as a value between 0 and 1). I am currently performing the interpolation on the CPU, but I would like to offload the computation to the GPU in order to compute intermediary frames faster.

Is there a way to do this using only OpenGL (ie. not OpenCL)? If so, how?

Answer Source

Assuming that vertices are stored in the same order in both buffers, you can simply bind each of the buffers to an attribute in the vertex shader. In combination with a uniform between which controls the interpolation (let's call it t) which goes from 0 (only first buffer) to 1 (only second buffer), you can perform the linear interpolation before writing to gl_Position. A shader could look somehow like the following:

in vec4 buffer1; //Bind buffer1 to this attribute
in vec4 buffer2; //Bind buffer2 to this attribute

uniform float t; //Interpolation parameter between 0 and 1

void main()
    gl_Position = (1 - t) * buffer1 + t * buffer2;
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