Re: OpenGL 1.4

• Subject: Re: OpenGL 1.4
• From: John Stauffer <email@hidden>
• Date: Thu, 19 Dec 2002 18:27:01 -0800

What hardware will provide full 1.4 support under 10.2.3? (I'm particularly wondering about the now-bundled depth/shadow extensions).

Thanks,
Dan

On Thursday, December 19, 2002, at 03:41 PM, John Stauffer wrote:

MacOS X 10.2.3 delivers OpenGL 1.4 and 13 new extensions.

* 13 New Extensions
GL ARB shadow ambient GL EXT s3tc texture compression
GL EXT shadow funcs GL EXT stencil two side
GL ARB fragment program GL ARB vertex blend
GL ARB window pos GL EXT multi draw arrays
GL NV light max exponent GL SGIS generate mipmap
GL Apple float pixels GL ATI point cull
GL ATI texture mirror once

OpenGL version 1.4, released on July 24, 2002, is the fourth revision since the original version 1.0. Version 1.4 is upward compatible with earlier versions, meaning that any program that runs with a 1.3, 1.2, 1.1, or 1.0 GL implementation will also run unchanged with a 1.4 GL implementation. In addition to numerous additions to the classical fixed-function GL pipeline in OpenGL 1.4, the OpenGL ARB also approved the ARB vertex program extension, which supports programmable vertex processing. Following are brief descriptions of each addition to OpenGL 1.4:

* Automatic Mipmap Generation - Setting the texture parameter GENERATE MIPMAP to TRUE introduces a side effect to any modification of the levelbase of a mipmap array, wherein all higher levels of the mipmap pyramid are recomputed automatically by successive filtering of the base level array.

* Blend Squaring extends the set of supported source and destination blend functions to permit squaring RGB and alpha values during blending.

* Changes to the Imaging Subset to include BlendEquation, BlendColor, and the BlendFunc modes CONSTANT COLOR, ONE MINUS CONSTANT COLOR, CONSTANT ALPHA, and ONE MINUS CONSTANT ALPHA (these features previously were available only in the optional imaging subset in versions 1.2 and 1.3 of the GL.)

* Depth and Shadows - Depth textures define a new texture internal format, DEPTH, normally used to represent depth values. Applications include image-based shadow casting, displacement mapping, and image-based rendering. Image-based shadowing is enabled with a new texture application mode defined by the parameter TEXTURE COMPARE > MODE.

* Fog Coordinates can be used in computing fog for a fragment, instead of using eye distance to the fragment, useful for more complex fog models

* Multiple Draw Arrays - Multiple primitives may be drawn in a single call using the MultiDrawArrays and MultiDrawElements commants.

* Point Parameters support additional geometric characteristics of points, allowing the size of a point to be affected by linear or quadratic distance attenuation, and increasing control of the mapping from point size to raster point area and point transparency. This effect may be used for distance attenuation in rendering particles or light points.

* Secondary Color may be varied even when lighting is disabled by specifying it as a vertex parameter with the SecondaryColor commands.

* Separate Blend Functions allow independent setting of the RGB and alpha blend functions for blend operations that require source and destination blend factors.

* Stencil Wrap operations INCR WRAP and DECR WRAP allow the stencil value to wrap around the range of stencil values instead of saturating to the minimum or maximum values on decrement or >> increment.

* Texture Crossbar Environment Mode extends the texture combine environment mode COMBINE by allowing use of the texture color from different texture units as sources to the texture combine function.

* Texture LOD Bias may be set to bias the computed lamda parameter used in texturing for mipmap level of detail selection, providing a means to blur or sharpen textures. LOD bias may be used for depth of field and other special visual effects, as well as for some types of image processing.

* Texture Mirrored Repeat extends the set of texture wrap modes with the mode MIRRORED REPEAT. This effectively defines a texture map twice as large as the original texture image in which the additional half, for each mirrored texture coordinate, is a mirror image of the original texture. Mirrored repeat can be used seamless tiling of a surface.

* Window Raster Position - The raster position may be set directly to specified window coordinates with the WindowPos commands, bypassing the transformation applied to RasterPos.


On Thursday, December 19, 2002, at 02:58 PM, Bobby Thomale wrote:

I notice in the release notes for 10.2.3 that OpenGL 1.4 is part of the
release.

Just out of curiosity [Apple people?] is there some sort of release notes on
what changed in OpenGL 1.4 that you could post?

No specific needs or concerns, I am mainly curious.

-- Bobby

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Bobby Thomale
Senior Software Developer
Inoveon Corporation
http://www.inoveon.com/
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