diff options
Diffstat (limited to 'src/mesa')
| -rw-r--r-- | src/mesa/shader/uniforms.c | 101 |
1 files changed, 54 insertions, 47 deletions
diff --git a/src/mesa/shader/uniforms.c b/src/mesa/shader/uniforms.c index 69758ea73f..b1fb90d020 100644 --- a/src/mesa/shader/uniforms.c +++ b/src/mesa/shader/uniforms.c @@ -319,6 +319,54 @@ lookup_uniform_parameter(GLcontext *ctx, GLuint program, GLint location, /** + * GLGL uniform arrays and structs require special handling. + * + * The GL_ARB_shader_objects spec says that if you use + * glGetUniformLocation to get the location of an array, you CANNOT + * access other elements of the array by adding an offset to the + * returned location. For example, you must call + * glGetUniformLocation("foo[16]") if you want to set the 16th element + * of the array with glUniform(). + * + * HOWEVER, some other OpenGL drivers allow accessing array elements + * by adding an offset to the returned array location. And some apps + * seem to depend on that behaviour. + * + * Mesa's gl_uniform_list doesn't directly support this since each + * entry in the list describes one uniform variable, not one uniform + * element. We could insert dummy entries in the list for each array + * element after [0] but that causes complications elsewhere. + * + * We solve this problem by encoding two values in the location that's + * returned by glGetUniformLocation(): + * a) index into gl_uniform_list::Uniforms[] for the uniform + * b) an array/field offset (0 for simple types) + * + * These two values are encoded in the high and low halves of a GLint. + * By putting the uniform number in the high part and the offset in the + * low part, we can support the unofficial ability to index into arrays + * by adding offsets to the location value. + */ +static void +merge_location_offset(GLint *location, GLint offset) +{ + *location = (*location << 16) | offset; +} + + +/** + * Separate the uniform location and parameter offset. See above. + */ +static void +split_location_offset(GLint *location, GLint *offset) +{ + *offset = *location & 0xffff; + *location = *location >> 16; +} + + + +/** * Called via ctx->Driver.GetUniformfv(). */ static void @@ -327,6 +375,9 @@ _mesa_get_uniformfv(GLcontext *ctx, GLuint program, GLint location, { struct gl_program *prog; GLint paramPos; + GLint offset; + + split_location_offset(&location, &offset); lookup_uniform_parameter(ctx, program, location, &prog, ¶mPos); @@ -357,6 +408,9 @@ _mesa_get_uniformiv(GLcontext *ctx, GLuint program, GLint location, { struct gl_program *prog; GLint paramPos; + GLint offset; + + split_location_offset(&location, &offset); lookup_uniform_parameter(ctx, program, location, &prog, ¶mPos); @@ -378,53 +432,6 @@ _mesa_get_uniformiv(GLcontext *ctx, GLuint program, GLint location, /** - * GLGL uniform arrays and structs require special handling. - * - * The GL_ARB_shader_objects spec says that if you use - * glGetUniformLocation to get the location of an array, you CANNOT - * access other elements of the array by adding an offset to the - * returned location. For example, you must call - * glGetUniformLocation("foo[16]") if you want to set the 16th element - * of the array with glUniform(). - * - * HOWEVER, some other OpenGL drivers allow accessing array elements - * by adding an offset to the returned array location. And some apps - * seem to depend on that behaviour. - * - * Mesa's gl_uniform_list doesn't directly support this since each - * entry in the list describes one uniform variable, not one uniform - * element. We could insert dummy entries in the list for each array - * element after [0] but that causes complications elsewhere. - * - * We solve this problem by encoding two values in the location that's - * returned by glGetUniformLocation(): - * a) index into gl_uniform_list::Uniforms[] for the uniform - * b) an array/field offset (0 for simple types) - * - * These two values are encoded in the high and low halves of a GLint. - * By putting the uniform number in the high part and the offset in the - * low part, we can support the unofficial ability to index into arrays - * by adding offsets to the location value. - */ -static void -merge_location_offset(GLint *location, GLint offset) -{ - *location = (*location << 16) | offset; -} - - -/** - * Seperate the uniform location and parameter offset. See above. - */ -static void -split_location_offset(GLint *location, GLint *offset) -{ - *offset = *location & 0xffff; - *location = *location >> 16; -} - - -/** * Called via ctx->Driver.GetUniformLocation(). * * The return value will encode two values, the uniform location and an |