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Chris Lux
11-16-2010, 05:31 PM
Hi,
i just ran into the same problem described here:
http://www.opengl.org/discussion_boards/ubbthreads.php?ubb=showflat&Number=286118

I am trying to use the gl_PrimitiveID variable to access a texture buffer in the tessellation control shader and the compiler complains that the variable is not defined and i should enable the EXT_gpu_shader_4 extension:


error C7531: global variable gl_PrimitiveID requires "#extension GL_EXT_gpu_shader4 : enable" before use

This is on a OpenGL 4.1 core context in a version 410 tessellation control shader. I am using a GTX 480 on ForceWare 260.93 (also tried 261.00 and 262.99).

This just stopped me cold here.

Just some shader snippets to illustrate the problem:



#version 410 core

// input/output definitions ///////////////////////////////////////////////////////////////////////
in per_vertex {
smooth vec2 texcoord;
} vertex_in[];

out per_vertex {
smooth vec2 texcoord;
} vertex_out[];

// uniform input definitions //////////////////////////////////////////////////////////////////////
uniform samplerBuffer edge_densities;

// output layout definitions //////////////////////////////////////////////////////////////////////
layout(vertices = 3) out;

[...]

vec4 tess_outer = texelFetch(edge_densities, gl_PrimitiveID * 2);
vec4 tess_inner = texelFetch(edge_densities, gl_PrimitiveID * 2 + 1);

gl_TessLevelOuter[0] = tess_outer.x;
gl_TessLevelOuter[1] = tess_outer.y;
gl_TessLevelOuter[2] = tess_outer.z;
gl_TessLevelInner[0] = tess_inner.x;

gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position;


-chris

aqnuep
11-17-2010, 07:57 AM
As I see it is a bug in the NVIDIA driver. I ended up with the same conclusion regarding to the other topic you've mentioned.

Chris Lux
11-17-2010, 09:51 AM
I am aware that it is a driver bug. This is the reason for posting it here.