'''OpenGL extension NV.texture_shader This module customises the behaviour of the OpenGL.raw.GL.NV.texture_shader to provide a more Python-friendly API Overview (from the spec) Standard OpenGL and the ARB_multitexture extension define a straightforward direct mechanism for mapping sets of texture coordinates to filtered colors. This extension provides a more functional mechanism. OpenGL's standard texturing mechanism defines a set of texture targets. Each texture target defines how the texture image is specified and accessed via a set of texture coordinates. OpenGL 1.0 defines the 1D and 2D texture targets. OpenGL 1.2 (and/or the EXT_texture3D extension) defines the 3D texture target. The ARB_texture_cube_map extension defines the cube map texture target. Each texture unit's texture coordinate set is mapped to a color using the unit's highest priority enabled texture target. This extension introduces texture shader stages. A sequence of texture shader stages provides a more flexible mechanism for mapping sets of texture coordinates to texture unit RGBA results than standard OpenGL. When the texture shader enable is on, the extension replaces the conventional OpenGL mechanism for mapping sets of texture coordinates to filtered colors with this extension's sequence of texture shader stages. Each texture shader stage runs one of 21 canned texture shader programs. These programs support conventional OpenGL texture mapping but also support dependent texture accesses, dot product texture programs, and special modes. (3D texture mapping texture shader operations are NOT provided by this extension; 3D texture mapping texture shader operations are added by the NV_texture_shader2 extension that is layered on this extension. See the NV_texture_shader2 specification.) To facilitate the new texture shader programs, this extension introduces several new texture formats and variations on existing formats. Existing color texture formats are extended by introducing new signed variants. Two new types of texture formats (beyond colors) are also introduced. Texture offset groups encode two signed offsets, and optionally a magnitude or a magnitude and an intensity. The new HILO (pronounced high-low) formats provide possibly signed, high precision (16-bit) two-component textures. Each program takes as input the stage's interpolated texture coordinate set (s,t,r,q). Each program generates two results: a shader stage result that may be used as an input to subsequent shader stage programs, and a texture unit RGBA result that becomes the texture color used by the texture unit's texture environment function or becomes the initial value for the corresponding texture register for register combiners. The texture unit RGBA result is always an RGBA color, but the shader stage result may be one of an RGBA color, a HILO value, a texture offset group, a floating-point value, or an invalid result. When both results are RGBA colors, the shader stage result and the texture unit RGBA result are usually identical (though not in all cases). Additionally, certain programs have a side-effect such as culling the fragment or replacing the fragment's depth value. The twenty-one programs are briefly described: 1. NONE - Always generates a (0,0,0,0) texture unit RGBA result. Equivalent to disabling all texture targets in conventional OpenGL. 2. TEXTURE_1D - Accesses a 1D texture via (s/q). 3. TEXTURE_2D - Accesses a 2D texture via (s/q,t/q). 4. TEXTURE_RECTANGLE_NV - Accesses a rectangular texture via (s/q,t/q). 5. TEXTURE_CUBE_MAP_ARB - Accesses a cube map texture via (s,t,r). 6. PASS_THROUGH_NV - Converts a texture coordinate (s,t,r,q) directly to a [0,1] clamped (r,g,b,a) texture unit RGBA result. 7. CULL_FRAGMENT_NV - Culls the fragment based on the whether each (s,t,r,q) is "greater than or equal to zero" or "less than zero". 8. OFFSET_TEXTURE_2D_NV - Transforms the signed (ds,dt) components of a previous texture unit by a 2x2 floating-point matrix and then uses the result to offset the stage's texture coordinates for a 2D non-projective texture. 9. OFFSET_TEXTURE_2D_SCALE_NV - Same as above except the magnitude component of the previous texture unit result scales the red, green, and blue components of the unsigned RGBA texture 2D access. 10. OFFSET_TEXTURE_RECTANGLE_NV - Similar to OFFSET_TEXTURE_2D_NV except that the texture access is into a rectangular non-projective texture. 11. OFFSET_TEXTURE_RECTANGLE_SCALE_NV - Similar to OFFSET_TEXTURE_2D_SCALE_NV except that the texture access is into a rectangular non-projective texture. 12. DEPENDENT_AR_TEXTURE_2D_NV - Converts the alpha and red components of a previous shader result into an (s,t) texture coordinate set to access a 2D non-projective texture. 13. DEPENDENT_GB_TEXTURE_2D_NV - Converts the green and blue components of a previous shader result into an (s,t) texture coordinate set to access a 2D non-projective texture. 14. DOT_PRODUCT_NV - Computes the dot product of the texture shader's texture coordinate set (s,t,r) with some mapping of the components of a previous texture shader result. The component mapping depends on the type (RGBA or HILO) and signedness of the stage's previous texture input. Other dot product texture programs use the result of this program to compose a texture coordinate set for a dependent texture access. The color result is undefined. 15. DOT_PRODUCT_TEXTURE_2D_NV - When preceded by a DOT_PRODUCT_NV program in the previous texture shader stage, computes a second similar dot product and composes the two dot products into (s,t) texture coordinate set to access a 2D non-projective texture. 16. DOT_PRODUCT_TEXTURE_RECTANGLE_NV - Similar to DOT_PRODUCT_TEXTURE_2D_NV except that the texture acces is into a rectangular non-projective texture. 17. DOT_PRODUCT_TEXTURE_CUBE_MAP_NV - When preceded by two DOT_PRODUCT_NV programs in the previous two texture shader stages, computes a third similar dot product and composes the three dot products into (s,t,r) texture coordinate set to access a cube map texture. 18. DOT_PRODUCT_REFLECT_CUBE_MAP_NV - When preceded by two DOT_PRODUCT_NV programs in the previous two texture shader stages, computes a third similar dot product and composes the three dot products into a normal vector (Nx,Ny,Nz). An eye vector (Ex,Ey,Ez) is composed from the q texture coordinates of the three stages. A reflection vector (Rx,Ry,Rz) is computed based on the normal and eye vectors. The reflection vector forms an (s,t,r) texture coordinate set to access a cube map texture. 19. DOT_PRODUCT_CONST_EYE_REFLECT_CUBE_MAP_NV - Operates like DOT_PRODUCT_REFLECT_CUBE_MAP_NV except that the eye vector (Ex,Ey,Ez) is a user-defined constant rather than composed from the q coordinates of the three stages. 20. DOT_PRODUCT_DIFFUSE_CUBE_MAP_NV - When used instead of the second DOT_PRODUCT_NV program preceding a DOT_PRODUCT_REFLECT_CUBE_MAP_NV or DOT_PRODUCT_CONST_EYE_REFLECT_CUBE_MAP_NV stage, the normal vector forms an (s,t,r) texture coordinate set to access a cube map texture. 21. DOT_PRODUCT_DEPTH_REPLACE_NV - When preceded by a DOT_PRODUCT_NV program in the previous texture shader stage, computes a second similar dot product and replaces the fragment's window-space depth value with the first dot product results divided by the second. The texture unit RGBA result is (0,0,0,0). The official definition of this extension is available here: http://www.opengl.org/registry/specs/NV/texture_shader.txt ''' from OpenGL import platform, constant, arrays from OpenGL import extensions, wrapper import ctypes from OpenGL.raw.GL import _types, _glgets from OpenGL.raw.GL.NV.texture_shader import * from OpenGL.raw.GL.NV.texture_shader import _EXTENSION_NAME def glInitTextureShaderNV(): '''Return boolean indicating whether this extension is available''' from OpenGL import extensions return extensions.hasGLExtension( _EXTENSION_NAME ) ### END AUTOGENERATED SECTION GL_OFFSET_TEXTURE_2D_BIAS_NV = GL_OFFSET_TEXTURE_BIAS_NV # alias GL_OFFSET_TEXTURE_2D_MATRIX_NV = GL_OFFSET_TEXTURE_MATRIX_NV # alias GL_OFFSET_TEXTURE_2D_SCALE_NV = GL_OFFSET_TEXTURE_SCALE_NV # alias