Operations that invlove comparison of mat4 matrices fails. Comparing the same matrices element by element succeeds
Hi,
I am experiencing the following failure with my ATI GPU Drivers. This could be a problem with the GL Shader Compiler that is used by the ATI Drivers.
Configuration
OS - Microsoft Windows XP Professional with SP2
GPU - ATO Radeon HD 2600 Pro
Driver version - 10.4 (from ATI Website)
Shader Program
The following shader returns incorrect result.
const mat4 ones_mat = mat4(1.0, 1.0, 1.0, 1.0,
1.0, 1.0, 1.0, 1.0,
1.0, 1.0, 1.0, 1.0,
1.0, 1.0, 1.0, 1.0);
const mat4 zeros_mat = mat4(0.0, 0.0, 0.0, 0.0,
0.0, 0.0, 0.0, 0.0,
0.0, 0.0, 0.0, 0.0,
0.0, 0.0, 0.0, 0.0);
bool matrix_equal(const in mat4 value, const in mat4 reference);
bool elements_equal(const in mat4 par, const in float value);
void main()
{
mat4 var;
var = ones_mat;
if( matrix_equal(var, ones_mat ) )
gl_FragColor = vec4(0.4,0.4,0.8,1.0);
}
bool matrix_equal(const in mat4 value, const in mat4 reference)
{
if(value == reference)
return true;
else
return false;
}
In the above shader, gl_FragColor should always be set to vec4(0.4,0.4,0.8,1.0) as the comparison operations should return true. The comparison opeartion fails and hence the shader returns the uninitialized value (black color).
Comparing the matrices element by element returns the correct result. The complete fragment shader has been attached.
We have verified the shader with other GPUs (NVIDIA) and they return the expected ouput. The problem has also been found with the latest ATI Drivers for Linux.
Linux Configuration
ATI Proprietary Linux Driver - 8.723
GPU - ATI Radeon HD 2600 Pro
Please let me know if a formal bug report needs to be raised. I am unsure of the forum it needs to be raised and hence posting it here.
Regards
Karthik
const mat4 ones_mat = mat4(1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0); bool matrix_equal(const in mat4 value, const in mat4 reference); bool elements_equal(const in mat4 par, const in float value); void main() { mat4 var; var = ones_mat; if( matrix_equal(var, ones_mat ) ) // if( elements_equal(var, 1.0) ) gl_FragColor = vec4(0.4,0.4,0.8,1.0); } bool matrix_equal(const in mat4 value, const in mat4 reference) { if(value == reference) return true; else return false; } bool elements_equal(const in mat4 par, const in float value) { bool ret = true; if(par[0][0] != value) ret = false; if(par[0][1] != value) ret = false; if(par[0][2] != value) ret = false; if(par[0][3] != value) ret = false; if(par[1][0] != value) ret = false; if(par[1][1] != value) ret = false; if(par[1][2] != value) ret = false; if(par[1][3] != value) ret = false; if(par[2][0] != value) ret = false; if(par[2][1] != value) ret = false; if(par[2][2] != value) ret = false; if(par[2][3] != value) ret = false; if(par[3][0] != value) ret = false; if(par[3][1] != value) ret = false; if(par[3][2] != value) ret = false; if(par[3][3] != value) ret = false; return ret; }
