| | '''OpenGL extension MESAX.texture_stack |
| | |
| | This module customises the behaviour of the |
| | OpenGL.raw.GL.MESAX.texture_stack to provide a more |
| | Python-friendly API |
| | |
| | Overview (from the spec) |
| | |
| | There are a number of circumstances where an application may wish to |
| | blend two textures out of a larger set of textures. Moreover, in some |
| | cases the selected textures may vary on a per-fragment basis within |
| | a polygon. Several examples include: |
| | |
| | 1. High dynamic range textures. The application stores several |
| | different "exposures" of an image as different textures. On a |
| | per-fragment basis, the application selects which exposures are |
| | used. |
| | |
| | 2. A terrain engine where the altitude of a point determines the |
| | texture applied to it. If the transition is from beach sand to |
| | grass to rocks to snow, the application will store each texture |
| | in a different texture map, and dynamically select which two |
| | textures to blend at run-time. |
| | |
| | 3. Storing short video clips in textures. Each depth slice is a |
| | single frame of video. |
| | |
| | Several solutions to this problem have been proposed, but they either |
| | involve using a separate texture unit for each texture map or using 3D |
| | textures without mipmaps. Both of these options have major drawbacks. |
| | |
| | This extension provides a third alternative that eliminates the major |
| | drawbacks of both previous methods. A new texture target, |
| | TEXTURE_2D_STACK, is added that functions identically to TEXTURE_3D in |
| | all aspects except the sizes of the non-base level images. In |
| | traditional 3D texturing, the size of the N+1 LOD is half the size |
| | of the N LOD in all three dimensions. For the TEXTURE_2D_STACK target, |
| | the height and width of the N+1 LOD is halved, but the depth is the |
| | same for all levels of detail. The texture then becomes a "stack" of |
| | 2D textures. The per-fragment texel is selected by the R texture |
| | coordinate. |
| | |
| | References: |
| | |
| | http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=011557 |
| | http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=000516 |
| | http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=011903 |
| | http://www.delphi3d.net/articles/viewarticle.php?article=terraintex.htm |
| | |
| | The official definition of this extension is available here: |
| | http://www.opengl.org/registry/specs/MESAX/texture_stack.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.MESAX.texture_stack import * |
| | from OpenGL.raw.GL.MESAX.texture_stack import _EXTENSION_NAME |
| |
|
| | def glInitTextureStackMESAX(): |
| | '''Return boolean indicating whether this extension is available''' |
| | from OpenGL import extensions |
| | return extensions.hasGLExtension( _EXTENSION_NAME ) |
| |
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| |
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| | |
