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