Vertex Shader. GL implementation bug?

[BilletAcc]

Is there any standart clarification on this?

I believe it’s an Intel HD Graphics drivers bug:

If would be great if some of you compiled this code on your machine (delete spaces):

https:// raw.githubusercontent. com/BilletAcc/Bug/main/main.c

[GClements]

Have you tried checking for errors using glGetShaderInfoLog and glGetProgramInfoLog?

[GClements]

@BilletAcc

	glLinkProgram(program);
	
	glBindAttribLocation(program, 0, "vertPos");
	glBindAttribLocation(program, 1, "vertNorm");

This is backwards. You need to call glBindAttribLocation before glLinkProgram. As it stands, the locations assigned to the input variables are unspecified. Changing which variables are active can reasonably be expected to affect the location assignments.

[BilletAcc]

Oh, true… Thanks a lot, now it all works perfectly!