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'''OpenGL extension SGIX.pixel_tiles |
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This module customises the behaviour of the |
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OpenGL.raw.GL.SGIX.pixel_tiles to provide a more |
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Python-friendly API |
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Overview (from the spec) |
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This extension deals with the interaction of existing GL functions that |
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read pixels from memory, applications that use grids of tiles of pixels, |
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and convolution. |
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Applications that deal with large multi-dimensional images sometimes |
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break the image into a grid of rectangular tiles of pixels. Such an |
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approach can help control memory use and expedite roaming through an |
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image that is large with respect to the available memory. |
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GL functions that cause pixels to be read from memory (e.g., DrawPixels |
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and TexImage2D) assume the pixels are stored as a single series of rows |
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of pixels. The grid of tiles is essentially a sequence of the structures |
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that the pixel reading functions assume. When an application that uses |
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tiling uses a GL function such as DrawPixels, it must iterate |
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through the tiles, either coalescing the tiles into a single tile in |
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preparation for a single GL call or calling the GL function for each tile. |
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The convolution operation imposes strict ordering on the way pixels |
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in a subimage that crosses tile boundaries must be transferred: the rows |
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of pixels transferred must span the entire subimage. Applications |
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that use tiles of pixels and convolution must copy the subimage to be |
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transferred from the grid of tiles to a contiguous region, then pass the |
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now-contiguous rows of pixels to the convolution function. If the |
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coalescing of tiles is not needed for some other reason or is not a |
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side effect of some necessary operation, it is just redundant movement |
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of the pixels. |
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This extension seeks to eliminate the extra copy of data by extending the |
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existing GL functions to accept, as a source of pixels in memory, a |
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grid of tiles of pixels in addition to the current sequence of rows |
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of pixels. |
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The official definition of this extension is available here: |
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http://www.opengl.org/registry/specs/SGIX/pixel_tiles.txt |
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''' |
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from OpenGL import platform, constant, arrays |
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from OpenGL import extensions, wrapper |
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import ctypes |
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from OpenGL.raw.GL import _types, _glgets |
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from OpenGL.raw.GL.SGIX.pixel_tiles import * |
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from OpenGL.raw.GL.SGIX.pixel_tiles import _EXTENSION_NAME |
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def glInitPixelTilesSGIX(): |
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'''Return boolean indicating whether this extension is available''' |
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from OpenGL import extensions |
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return extensions.hasGLExtension( _EXTENSION_NAME ) |
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