OpenGL.GL.NV.texture_shader3

OpenGL extension NV.texture_shader3

This module customises the behaviour of the OpenGL.raw.GL.NV.texture_shader3 to provide a more Python-friendly API

Overview (from the spec)

NV_texture_shader3 extends the NV_texture_shader functionality by adding several new texture shader operations, extending several existing texture shader operations, adding a new HILO8 internal format, and adding new and more flexible re-mapping modes for dot product and dependent texture shader operations.

See the NV_texture_shader extension for information about the texture shader operational model.

The fourteen new texture shader operations are:

<offset textures>

24. OFFSET_PROJECTIVE_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.

25. OFFSET_PROJECTIVE_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.

26. OFFSET_PROJECTIVE_TEXTURE_RECTANGLE_NV - Similar to OFFSET_TEXTURE_2D_NV except that the texture access is into a rectangular non-projective texture.

27. OFFSET_PROJECTIVE_TEXTURE_RECTANGLE_SCALE_NV - Similar to OFFSET_PROJECTIVE_TEXTURE_2D_SCALE_NV except that the texture access is into a rectangular non-projective texture.

28. OFFSET_HILO_TEXTURE_2D_NV - Similar to OFFSET_TEXTURE_2D_NV but uses a (higher-precision) HILO base format texture rather than a DSDT-type base format.

29. OFFSET_HILO_TEXTURE_RECTANGLE_NV - Similar to OFFSET_TEXTURE_RECTANGLE_NV but uses a (higher-precision) HILO base format texture rather than a DSDT-type base format.

30. OFFSET_HILO_PROJECTIVE_TEXTURE_2D_NV - Similar to OFFSET_PROJECTIVE_TEXTURE_2D_NV but uses a (higher-precision) HILO base format texture rather than a DSDT-type base format.

31. OFFSET_HILO_PROJECTIVE_TEXTURE_RECTANGLE_NV - Similar to OFFSET_PROJECTIVE_TEXTURE_RECTANGLE_NV but uses a (higher-precision) HILO base format texture rather than a DSDT-type base format.

(There are no "offset HILO texture scale" operations because HILO textures have only two components with no third component for scaling.)

<dependent textures>

32. DEPENDENT_HILO_TEXTURE_2D_NV - Converts the hi and lo components of a previous shader HILO result into an (s,t) texture coordinate set to access a 2D non-projective texture.

33. DEPENDENT_RGB_TEXTURE_3D_NV - Converts the red, green, and blue components of a previous shader RGBA result into an (s,t,r) texture coordinate set to access a 3D non-projective texture.

34. DEPENDENT_RGB_TEXTURE_CUBE_MAP_NV - Converts the red, green, and blue components of a previous shader RGBA result into an (s,t,r) texture coordinate set to access a cube map texture.

<dot product pass through>

35. DOT_PRODUCT_PASS_THROUGH_NV - Computes a dot product in the manner of the DOT_PRODUCT_NV operation and the result is [0,1] clamped and smeared to generate the texture unit RGBA result.

<dot product textures>

36. DOT_PRODUCT_TEXTURE_1D_NV - Computes a dot product in the manner of the DOT_PRODUCT_NV operation and uses the result as the s texture coordinate to access a 2D non-projective texture.

<dot product depth replace>

37. DOT_PRODUCT_AFFINE_DEPTH_REPLACE_NV - Computes a dot product in the manner of the DOT_PRODUCT_NV operation and the result is [0,1] clamped and replaces the fragment's window-space depth value. The texture unit RGBA result is (0,0,0,0).

Two new internal texture formats have been added: HILO8_NV and SIGNED_HILO8_NV. These texture formats allow HILO textures to be stored in half the space; still the filtering for these internal texture formats is done with 16-bit precision.

One new unsigned RGBA dot product mapping mode (FORCE_BLUE_TO_ONE_NV) forces the blue component to be 1.0 before computing a dot product.

The official definition of this extension is available here: http://www.opengl.org/registry/specs/NV/texture_shader3.txt