Hi All

I realize OpenGL draws a quad as 2 triangles with barycentric interpolation for each one. But it looks "not symmetric" (attach), that confuses users and produces unneeded questions. Is there a way to change this, or it's unavoidable?

Thank you

Simply draw the quad by yourself and determine the color values set for each triangle or use a shader is the best bet for doing this

Turn your quads into triangles, this might help.

In OpenGL, values (i.e. colours) are interpolated across triangles between the vertex and fragment shader regardless if you want it to do that or not. Am I guessing you are drawing the colour per vertex rather than per pixel?