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[i915] Add comments about how cube texture layout works.

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This commit is contained in:
Eric Anholt 2008-03-18 17:49:31 -07:00
parent 45adf29ed0
commit c2814f2a3f
1 changed files with 107 additions and 2 deletions
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109
src/mesa/drivers/dri/i915/i915_tex_layout.c
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@ -25,8 +25,8 @@
*
**************************************************************************/
/* Code to layout images in a mipmap tree for i915 and i945
* respectively.
/** @file i915_tex_layout.c
* Code to layout images in a mipmap tree for i830M-GM915 and G945 and beyond.
*/
#include "intel_mipmap_tree.h"
@ -55,6 +55,50 @@ static GLint step_offsets[6][2] = {
{-1, 1}
};
/**
* Cube texture map layout for i830M-GM915.
*
* Hardware layout looks like:
*
* +-------+-------+
* | | |
* | | |
* | | |
* | +x | +y |
* | | |
* | | |
* | | |
* | | |
* +---+---+-------+
* | | | |
* | +x| +y| |
* | | | |
* | | | |
* +-+-+---+ +z |
* | | | | |
* +-+-+ +z| |
* | | | |
* +-+-+---+-------+
* | | |
* | | |
* | | |
* | -x | -y |
* | | |
* | | |
* | | |
* | | |
* +---+---+-------+
* | | | |
* | -x| -y| |
* | | | |
* | | | |
* +-+-+---+ -z |
* | | | | |
* +-+-+ -z| |
* | | | |
* +-+---+-------+
*
*/
static void
i915_miptree_layout_cube(struct intel_context *intel,
struct intel_mipmap_tree * mt)
@ -199,6 +243,67 @@ i915_miptree_layout(struct intel_context *intel, struct intel_mipmap_tree * mt)
return GL_TRUE;
}
/**
* Cube texture map layout for GM945 and later.
*
* The hardware layout looks like the 830-915 layout, except for the small
* sizes. A zoomed in view of the layout for 945 is:
*
* +-------+-------+
* | 8x8 | 8x8 |
* | | |
* | | |
* | +x | +y |
* | | |
* | | |
* | | |
* | | |
* +---+---+-------+
* |4x4| | 8x8 |
* | +x| | |
* | | | |
* | | | |
* +---+ | +z |
* |4x4| | |
* | +y| | |
* | | | |
* +---+ +-------+
*
* ...
*
* +-------+-------+
* | 8x8 | 8x8 |
* | | |
* | | |
* | -x | -y |
* | | |
* | | |
* | | |
* | | |
* +---+---+-------+
* |4x4| | 8x8 |
* | -x| | |
* | | | |
* | | | |
* +---+ | -z |
* |4x4| | |
* | -y| | |
* | | | |
* +---+ +---+---+---+---+---+---+---+---+---+
* |4x4| |4x4| |2x2| |2x2| |2x2| |2x2|
* | +z| | -z| | +x| | +y| | +z| | -x| ...
* | | | | | | | | | | | |
* +---+ +---+ +---+ +---+ +---+ +---+
*
* The bottom row continues with the remaining 2x2 then the 1x1 mip contents
* in order, with each of them aligned to a 4x4 block boundary. Thus, for
* 32x32 cube maps and smaller, the bottom row layout is going to dictate the
* pitch of the tree. For a tree with 4x4 images, the pitch is at least
* 14 * 8 = 112 texels, for 2x2 it is at least 12 * 8 texels, and for 1x1
* it is 6 * 8 texels.
*/
static void
i945_miptree_layout_cube(struct intel_context *intel,
struct intel_mipmap_tree * mt)