| |
| Name |
| SUNX_constant_data |
| |
| Name Strings |
| |
| GL_SUNX_constant_data |
| |
| Contact |
| |
| Ron Bielaski, Sun (Ron.Bielaski 'at' eng.sun.com) |
| Jack Middleton, Sun (Jack.Middleton 'at' eng.sun.com) |
| |
| Status |
| |
| Shipping |
| |
| Version |
| |
| $Date: 1999/12/28 01:40:37 $ $Revision: 1.5 $ |
| SUN Date: 99/06/25 15:06:46 Revision: 1.2 |
| |
| Number |
| |
| 163 |
| |
| Dependencies |
| |
| None |
| |
| Overview |
| |
| This extension allows the pixel data specified by the |
| application to be used internally without making a second copy. |
| This extension affects how the pixel data in client memory is |
| interpreted and therefore affects DrawPixels, Bitmap, |
| PolygonStipple, TexImage1D, TexImage2D, TexImage3DEXT, |
| ColorTableSGI. |
| |
| New Procedures and Functions |
| |
| void FinishTextureSUNX(void) |
| |
| New Tokens |
| |
| Accepted by the <pname> parameter PixelStore*() |
| |
| UNPACK_CONSTANT_DATA_SUNX 0x81D5 |
| |
| Accepted by <pname> parameter of GetTexLevelParameter() |
| |
| TEXTURE_CONSTANT_DATA_SUNX 0x81D6 |
| |
| |
| Additions to Chapter 2 of the GL Specification (OpenGL Operation) |
| |
| When TexImage1D(), TexImage2D(), TexImage3DEXT() is called, |
| specifying PixelStore*() with pname UNPACK_CONSTANT_DATA_SUNX set to |
| TRUE will allow the implementation to use the application provided data |
| pointer internally thereby avoiding a second copy. If pixel transfer is |
| enabled when using this pixel store mode or if the constant directive |
| cannot be honored , then the constant directive will be ignored and a |
| copy will be made internally. Thus, specifying "constant" data |
| directive does not prohibit the implementation from making a copy, |
| rather it is treated as a hint by the implementation to avoid making a |
| second copy if possible. Note that if UNPACK_CONSTANT_DATA_SUNX is set |
| to TRUE, and all the pixel store values are not default values then the |
| constant hint will not be honored. |
| |
| |
| A TexSubImage*() will always make a copy of the existing texture |
| image before updating the subimage except when the scenario given below |
| is true. |
| |
| If a TexSubImage1D(), TexSubImage2D(), TexSubImage3DEXT() is |
| called with PixelStore pname UNPACK_CONSTANT_DATA_SUNX set to TRUE on a |
| constant texture, then the address of the start of the texture image is |
| computed using the specified xoffset, yoffset, zoffset. If this |
| computed address matches the start address of the currently used |
| constant texture then no action is taken. If the addresses do not match |
| then a copy is first made of the entire texture and then the subimage |
| is updated in this copy. A texture is a "constant texture" if at the |
| time of the specification of the texture no copy was made. This |
| attribute can be queried as described later. |
| |
| Before an application changes a part or all of the texture image that |
| has been specified as a constant texture image, it is necessary to |
| call FinishTextureSUNX() to ensure that the library has completed all |
| its processing with the currently specified constant texture image |
| before the changes are applied to this constant texture image by the |
| application. |
| |
| If a CopyTexImage[1/2/3]D or CopyTexSubImage[1/2/3]D is made and |
| the existing texture image is constant, then a copy is made |
| internally before executing the CopyTex* calls. |
| |
| |
| In immediate mode, for DrawPixels()/Bitmap(), specifying constant data |
| is not meaningful since data does not have a life beyond the call |
| itself. |
| |
| A texture image/raster image or bitmap could be specified as constant |
| at the time of the creation of the display list. If pixelmap/pixel |
| transfer is enabled before calling the display list, then a copy is |
| made internally and the data is no longer constant. |
| |
| It is invalid to specify a texture subimage as constant in a display |
| list. Doing so, will result in an INVALID_OPERATION error. |
| |
| Query support |
| ------------- |
| The pixel store value for the constant data that has been set can be |
| inquired using Get() with pname set to UNPACK_CONSTANT_DATA_SUNX. |
| |
| When TexImage*D() is executed with target PROXY_TEXTURE_[1,2,3]D then |
| the state value of TEXTURE_CONSTANT_DATA_SUNX will be set to 0 if |
| the texture data cannot be stored as constant, otherwise the value |
| will be 1. |
| |
| The constant nature of the texture data can be inquired using |
| GetTexLevelParameter*() with pname TEXTURE_CONSTANT_DATA_SUNX and |
| target PROXY_TEXTURE_[1,2,3]D . If the target is TEXTURE_[1,2,3]D and |
| pname is TEXTURE_CONSTANT_DATA_SUNX, then the value returned is TRUE |
| if the the texture image defined at this level is currently |
| constant. |
| |
| Note that a texture image may become non-constant (that is an internal |
| copy may be made) at the time when the texture is used rather than at a |
| time when the texture is specified. If interested, an application could |
| inquire the constant nature of the texture data after the texture has |
| been used for rendering. |
| |
| Additions to the GLX / WGL / AGL Specifications |
| |
| None |
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| GLX Protocol |
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| None |
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| Errors |
| |
| None |
| |
| New State |
| |
| ??? |
| (will affect both pixel pack/unpack and texture state) |
| |
| New Implementation Dependent State |
| |
| None |
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| Revision History |
| |
| 6/24/99 - Updated name string to SUNX instead of SUN. |
| Added fields from the new extension template. |
| |
| |
