changing uniforms expensive?

Graphics and GPU Programming Programming

Started by bimm February 18, 2012 03:22 PM

1 comment, last by V-man 12 years, 2 months ago

102

Author

February 18, 2012 03:22 PM

I have around 4000 buffers that need to be drawn, and I change my shader uniform 'translation' value before each drawing. Should I just store the entire translation+position in the vertex position instead to avoid changing that uniform rapidly? (it would require a larger position datatype to hold the range)

japro

887

February 18, 2012 03:26 PM

If storing the transform in the vertex data is an option then why not simply store the transformed vertices to begin with?

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V-man

813

February 20, 2012 09:36 PM

You can store the positions in a GL_RGBA32F texture.
Send a texcoord value (1 dimentionsal) to read the GL_RGBA32F texture from your vertex shader.

Sig: http://glhlib.sourceforge.net
an open source GLU replacement library. Much more modern than GLU.
float matrix[16], inverse_matrix[16];
glhLoadIdentityf2(matrix);
glhTranslatef2(matrix, 0.0, 0.0, 5.0);
glhRotateAboutXf2(matrix, angleInRadians);
glhScalef2(matrix, 1.0, 1.0, -1.0);
glhQuickInvertMatrixf2(matrix, inverse_matrix);
glUniformMatrix4fv(uniformLocation1, 1, FALSE, matrix);
glUniformMatrix4fv(uniformLocation2, 1, FALSE, inverse_matrix);