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'''OpenGL extension SGIX.sprite |
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This module customises the behaviour of the |
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OpenGL.raw.GL.SGIX.sprite 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 provides support for viewpoint dependent alignment |
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of geometry, in particular geometry that rotates about a point or |
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a specified axis to face the eye point. The primary use is for |
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quickly rendering roughly cylindrically or spherically symmetric |
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objects, e.g. trees, smoke, clouds, etc. using geometry textured |
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with a partially transparent texture map. |
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Rendering sprite geometry requires applying a transformation to |
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primitives before the current model view. This matrix includes a |
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rotation which is computed based on the current model view matrix |
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and a translation which is specified explicitly |
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(SPRITE_TRANSLATION_SGIX). The current model view matrix itself |
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is not modified. |
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Primitives are first transformed by a rotation, depending on the |
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sprite mode: |
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SPRITE_AXIAL_SGIX: The front of the object is rotated about |
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an axis so that it faces the eye as much as the axis |
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constraint allows. This is used for roughly rendering cylindrical |
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objects such as trees in visual simulation. |
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SPRITE_OBJECT_ALIGNED_SGIX: The front of the object is |
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rotated about a point to face the eye with the remaining |
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rotational degree of freedom specified by aligning the top |
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of the object with a specified axis in object coordinates. |
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This is used for spherical objects and special effects such |
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as smoke which must maintain an alignment in object |
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coordinates for realism. |
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SPRITE_EYE_ALIGNED_SGIX: The front of the object is rotated |
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about a point to face the eye with the remaining rotational |
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degree of freedom specified by aligning the top of the object |
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with a specified axis in eye coordinates. This is used for |
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rendering sprites which must maintain an alignment on the |
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screen, such as 3D annotations. |
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The axis of rotation or alignment, SPRITE_AXIS_SGIX, can be |
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an arbitrary direction to support geocentric coordinate frames |
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in which "up" is not along X, Y or Z. |
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Sprite geometry is modeled in a canonical frame: +Z is the up |
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vector. -Y is the front vector which is rotated to point towards |
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the eye. In the discussion below, the eye vector is the vector to |
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the eye from the origin of the model view frame translated by the |
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sprite position. |
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The official definition of this extension is available here: |
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http://www.opengl.org/registry/specs/SGIX/sprite.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.sprite import * |
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from OpenGL.raw.GL.SGIX.sprite import _EXTENSION_NAME |
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def glInitSpriteSGIX(): |
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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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glSpriteParameterfvSGIX=wrapper.wrapper(glSpriteParameterfvSGIX).setInputArraySize( |
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'params', None |
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) |
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glSpriteParameterivSGIX=wrapper.wrapper(glSpriteParameterivSGIX).setInputArraySize( |
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'params', None |
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) |
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