Difference between revisions of "GPU Textures"

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(Rewrite most of this page.)
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This page describes the [[GPU_Commands|GPU commands]] used for textures.
 
This page describes the [[GPU_Commands|GPU commands]] used for textures.
  
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== Command set 0x0081 ==
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== Texture unit setup: Register 0x80 ==
 +
Register 0x80 is used to enable individual texture units.
 +
 
 
{| class="wikitable" border="1"
 
{| class="wikitable" border="1"
−
!  Command Index
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!  Bit
−
!  CommandID
 
−
!  Parameter
 
 
!  Description
 
!  Description
 
|-
 
|-
 
| 0
 
| 0
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| 0x0081
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| Enable texture unit 0.
−
|
 
−
| This is used to set the current texture info used for rendering.
 
 
|-
 
|-
 
| 1
 
| 1
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| 0x008E
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| Enable texture unit 1.
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| u32 color type
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|-
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| This sets the current texture color type.
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| 2
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| Enable texture unit 2.
 
|}
 
|}
  
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Textures are initially disabled when beginning rendering for each mesh, this command set also enables textures. This command set is used for index0, commands 0x0091 and 0x0099 are used for index1-index2.
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== Configuration of texture unit 0 ==
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=== Texture info parameter structure for command 0x0081 ===
 
 
{| class="wikitable" border="1"
 
{| class="wikitable" border="1"
−
!  Index Word
+
!  Register ID
 
!  Description
 
!  Description
 
|-
 
|-
−
| 0
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| 0x0081
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| ?
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| Border color (unverified)
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|-
 +
| 0x0082
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| Bits 16-31 are the texture width. Bits 0-15 are the texture height. The maximum texture size in either direction is 1024.
 +
|-
 +
| 0x0083
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| Texture parameters (filtering, wrapping), see below.
 +
|-
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| 0x0084
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| LOD setup?
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|-
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| 0x0085
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| Physical address of texture data (divided by 8).
 +
|-
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| 0x0086
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| Physical address of texture data for cube mapping?
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|-
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| 0x0087
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| Physical address of texture data for cube mapping?
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|-
 +
| 0x0088
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| Physical address of texture data for cube mapping?
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|-
 +
| 0x0089
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| Physical address of texture data for cube mapping?
 
|-
 
|-
−
| 1
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| 0x008A
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| The low u16 is the texture image width, and the high u16 is the texture image height.
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| Physical address of texture data for cube mapping?
 
|-
 
|-
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| 2
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| 0x008B
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| Texture parameters, initialized by glTexParameter().
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| Shadow related?
 
|-
 
|-
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| 3
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| 0x008E
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| ?
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| Texture format (see below)
 +
|}
 +
 
 +
== Configuration of texture units 1 and 2 ==
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Texture units 1 and 2 use a configuration block similar to the one of texture unit 0. They are based at registers 0x0091 and 0x0099.
 +
 
 +
{| class="wikitable" border="1"
 +
!  Index word
 +
!  Description
 
|-
 
|-
−
| 4
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| 0-4
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| Texture image data physical address >> 3.
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| Same as for texture unit 0
 
|-
 
|-
−
| 5-9
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| 5
−
| Value zero
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| Texture format (see below)
 
|}
 
|}
 +
 +
== Configuration of texture unit 3 ==
 +
The configuration block for texture unit 3 seems to be vastly different from the other texture units. Instead, registers 0x00A8 through 0x00B7 are used to configure procedural texturing features.
  
 
== Texture info parameter structure for commands 0x0091 and 0x0099 ==
 
== Texture info parameter structure for commands 0x0091 and 0x0099 ==

Revision as of 15:32, 11 April 2015

This page describes the GPU commands used for textures.

Texture unit setup: Register 0x80

Register 0x80 is used to enable individual texture units.

Bit Description
0 Enable texture unit 0.
1 Enable texture unit 1.
2 Enable texture unit 2.

Configuration of texture unit 0

Register ID Description
0x0081 Border color (unverified)
0x0082 Bits 16-31 are the texture width. Bits 0-15 are the texture height. The maximum texture size in either direction is 1024.
0x0083 Texture parameters (filtering, wrapping), see below.
0x0084 LOD setup?
0x0085 Physical address of texture data (divided by 8).
0x0086 Physical address of texture data for cube mapping?
0x0087 Physical address of texture data for cube mapping?
0x0088 Physical address of texture data for cube mapping?
0x0089 Physical address of texture data for cube mapping?
0x008A Physical address of texture data for cube mapping?
0x008B Shadow related?
0x008E Texture format (see below)

Configuration of texture units 1 and 2

Texture units 1 and 2 use a configuration block similar to the one of texture unit 0. They are based at registers 0x0091 and 0x0099.

Index word Description
0-4 Same as for texture unit 0
5 Texture format (see below)

Configuration of texture unit 3

The configuration block for texture unit 3 seems to be vastly different from the other texture units. Instead, registers 0x00A8 through 0x00B7 are used to configure procedural texturing features.

Texture info parameter structure for commands 0x0091 and 0x0099

Index Word Description
4-0 Same as command 0x0081.
5 Color type

Texture parameters

Bit Description GL parameter name
0 Normally this is value 0.
1 0 = GL_NEAREST, 1 = GL_LINEAR. GL_TEXTURE_MAG_FILTER
2 1 = GL_LINEAR, GL_LINEAR_MIPMAP_NEAREST, or GL_LINEAR_MIPMAP_LINEAR. Value zero otherwise. GL_TEXTURE_MIN_FILTER
3 Unused? ?
5-4 2 = texture color type 0xC, 0 otherwise.(Enable/disable texture data compression?) 0 = unknown, 1 = unknown, 3 = same effect as value 2.
7-6 Unused
11-8 0 = GL_CLAMP_TO_EDGE, 1=unknown, 2=GL_REPEAT, 3=unknown. GL_TEXTURE_WRAP_S
15-12 Same values as GL_TEXTURE_WRAP_S. GL_TEXTURE_WRAP_T
24 1 = GL_NEAREST_MIPMAP_LINEAR, or GL_LINEAR_MIPMAP_LINEAR. Value zero otherwise. GL_TEXTURE_MIN_FILTER
27-25 Unused?
30-28 When some flag=1: value1=GL_TEXTURE_2D, value0 when the input parameter is not GL_TEXTURE_2D. When some flag=0: 0=GL_TEXTURE_2D, 1-4=unknown. ?
31 Unused? ?

Texture color types

Value Description GL Format GL Data Type
0x0 RGBA8888 GL_RGBA / DMP-extension constant 0x6752 GL_UNSIGNED_BYTE
0x1 BGR888 GL_RGB / DMP-extension constant 0x6754 GL_UNSIGNED_BYTE
0x2 RGBA5551 GL_RGBA / DMP-extension constant 0x6752 GL_UNSIGNED_SHORT_5_5_5_1
0x3 BGR565 GL_RGB / DMP-extension constant 0x6754 GL_UNSIGNED_SHORT_5_6_5
0x4 RGBA4444 GL_RGBA / DMP-extension constant 0x6752 GL_UNSIGNED_SHORT_4_4_4_4
0x5 Tiled RGB565 GL_LUMINANCE_ALPHA(?) / DMP-extension constant 0x6758(?) GL_UNSIGNED_BYTE(?)
0x6 Tiled BGR888 DMP-extension constants 0x6700 / 0x6759 GL_UNSIGNED_BYTE
0x7 GL_LUMINANCE / DMP-extension constant 0x6757 GL_UNSIGNED_BYTE
0x8 GL_ALPHA / DMP-extension constant 0x6756 GL_UNSIGNED_BYTE
0x9 ? GL_LUMINANCE_ALPHA / DMP-extension constant 0x6758 DMP-extension constant 0x6760
0xA ? GL_LUMINANCE / DMP-extension constant 0x6757 DMP-extension constant 0x6761
0xB ? GL_ALPHA / DMP-extension constant 0x6756 DMP-extension constant 0x6761
0xC Compression related? DMP-extension constant 0x675A
0xD ? DMP-extension constant 0x675B
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