| '''OpenGL extension ARB.derivative_control |
| |
| This module customises the behaviour of the |
| OpenGL.raw.GL.ARB.derivative_control to provide a more |
| Python-friendly API |
| |
| Overview (from the spec) |
| |
| This extension provides control over the spacial granularity at which the |
| underlying implementation computes derivatives. |
| |
| For example, for the coarse-granularity derivative, a single x derivative |
| could be computed for each 2x2 group of pixels, using that same derivative |
| value for all 4 pixels. For the fine-granularity derivative, two |
| derivatives could be computed for each 2x2 group of pixels; one for the top |
| row and one for the bottom row. Implementations vary somewhat on how this |
| is done. |
| |
| To select the coarse derivative, use: |
| |
| dFdxCoarse(p) |
| dFdyCoarse(p) |
| fwidthCoarse(p) |
| |
| To select the fine derivative, use: |
| |
| dFdxFine(p) |
| dFdyFine(p) |
| fwidthFine(p) |
| |
| To select which ever is "better" (based on performance, API hints, or other |
| factors), use: |
| |
| dFdx(p) |
| dFdy(p) |
| fwidth(p) |
| |
| This last set is the set of previously existing built-ins for derivatives, |
| and continues to work in a backward compatible way. |
| |
| The official definition of this extension is available here: |
| http://www.opengl.org/registry/specs/ARB/derivative_control.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.ARB.derivative_control import * |
| from OpenGL.raw.GL.ARB.derivative_control import _EXTENSION_NAME |
|
|
| def glInitDerivativeControlARB(): |
| '''Return boolean indicating whether this extension is available''' |
| from OpenGL import extensions |
| return extensions.hasGLExtension( _EXTENSION_NAME ) |
|
|
|
|
| |
