GPU Textures
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 |