Materials (Metroid Prime): Difference between revisions
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The format for '''materials''' is seen in both the [[CMDL (Metroid Prime)|CMDL]] and [[MREA (File Format)|MREA]] formats and is identical in both. This particular material format appears in both Metroid Prime and Metroid Prime 2 with minor differences. | The format for '''materials''' is seen in both the [[CMDL (Metroid Prime)|CMDL]] and [[MREA (File Format)|MREA]] formats and is identical in both. This particular material format appears in both Metroid Prime and Metroid Prime 2 with minor differences. | ||
{{research| | {{research|minor|MP1's materials are completely understood, but MP2 introduced two new values that are both unknown.}} | ||
__TOC__ | __TOC__ | ||
== GX | == GX Overview == | ||
The materials system in Metroid Prime is heavily dependent on the GameCube and Wii's graphics system, GX. GX is a fixed-function graphics pipeline, similar to old versions of OpenGL. In GX, rendering is done through a series of steps called '''T'''exture '''E'''n'''V'''ironment Stages, or or TEV stages for short. | The materials system in Metroid Prime is heavily dependent on the GameCube and Wii's graphics system, GX. GX is a fixed-function graphics pipeline, similar to old versions of OpenGL. In GX, rendering is done through a series of steps called '''T'''exture '''E'''n'''V'''ironment Stages, or or TEV stages for short. | ||
Lighting calculations and tex coord generation are done per-vertex and passed along to TEV; the results of the lighting calculations are saved into up to two color channels that can be used as TEV inputs (as the rasterized vertex color). Each TEV stage takes in four color inputs and four alpha inputs, from one of eight sources. Then these four input colors are combined into one output color, and the output is saved into one of four registers, which can subsequently be used as input in the next TEV stages. The final stage must always save its output into the "previous TEV stage" register; that register is used as the final pixel color that gets displayed onscreen. | |||
== Material Set Format == | == Material Set Format == | ||
Line 78: | Line 76: | ||
| long | | long | ||
| 1 | | 1 | ||
| '''Group index''' | |||
|- | |- | ||
| long | | long | ||
Line 98: | Line 96: | ||
| long | | long | ||
| 1 | | 1 | ||
| '''Reflection indirect texture slot index''' ''(note: only present if flag 0x400 is set!)'' | |||
|- | |- | ||
| long | | long | ||
| 1 | | 1 | ||
| '''Color channel | | '''Color channel count''' (CC) | ||
|- | |- | ||
| long | | long | ||
| CC | | CC | ||
| '''Color channel flags''' | | '''Color channel flags''' ''(note: only one flag value, but you must advance 4*CC bytes instead of 4 for some reason)'' | ||
|- | |- | ||
| long | | long | ||
Line 115: | Line 113: | ||
==== Flags ==== | ==== Flags ==== | ||
These are the known flag settings: | These are simple boolean settings that can be toggled on and off on each material. These are the known flag settings: | ||
{| class="wikitable" | {| class="wikitable" | ||
Line 124: | Line 122: | ||
| 0 | | 0 | ||
| 0x1 | | 0x1 | ||
| | | Unused, always set ''(never set in Echoes)'' | ||
|- | |- | ||
| 1 | | 1 | ||
| 0x2 | | 0x2 | ||
| | | Unused, always set | ||
|- | |- | ||
| 2 | | 2 | ||
| 0x4 | | 0x4 | ||
| | | Unused, never set | ||
|- | |- | ||
| 3 | | 3 | ||
| 0x8 | | 0x8 | ||
| | | Has Konst values | ||
|- | |- | ||
| 4 | | 4 | ||
| 0x10 | | 0x10 | ||
| | | Transparent | ||
|- | |- | ||
| 5 | | 5 | ||
| 0x20 | | 0x20 | ||
| | | Masked alpha (compare threshold is hardcoded at 0.25) | ||
|- | |- | ||
| 6 | | 6 | ||
Line 152: | Line 150: | ||
| 7 | | 7 | ||
| 0x80 | | 0x80 | ||
| Enable | | Enable Z-writes | ||
|- | |- | ||
| 8 | | 8 | ||
| 0x100 | | 0x100 | ||
| | | Enable Samus's reflection, using the eye position and projection direction from the surface header | ||
|- | |- | ||
| 9 | | 9 | ||
| 0x200 | | 0x200 | ||
| | | Shadow occluder mesh; meshes using this material are not rendered, but can be used to cast dynamic shadows on actors | ||
|- | |- | ||
| 10 | | 10 | ||
| 0x400 | | 0x400 | ||
| Enable | | Enable indirect texture stage for reflections | ||
|- | |- | ||
| 11 | | 11 | ||
| 0x800 | | 0x800 | ||
| | | Indicates a lightmap is present; no ingame effect | ||
|- | |- | ||
| 12 | | 12 | ||
| 0x1000 | | 0x1000 | ||
| | | Unused, always set ''(never set in Echoes)'' | ||
|- | |- | ||
| 13 | | 13 | ||
| 0x2000 | | 0x2000 | ||
| Enable | | Enable first UV coordinate to use short array instead of float array (used for world lightmaps) | ||
|- | |- | ||
| 14 | | 14 | ||
| 0x4000 | | 0x4000 | ||
| {{unknown| | | {{unknown|In MP1, unused, never set; in Echoes, unknown}} | ||
|- | |- | ||
| 15 | | 15 | ||
| 0x8000 | | 0x8000 | ||
| {{unknown| | | {{unknown|In MP1, unused, never set; in Echoes, unknown}} | ||
|- | |- | ||
| | | 16-31 | ||
| 0xFFFF0000 | |||
| TEV texture flags; a bit set indicates that the corresponding TEV stage uses a texture. No ingame effect. | |||
| | |||
| | |||
|} | |} | ||
==== Vertex Attribute Flags ==== | ==== Vertex Attribute Flags ==== | ||
These flags are generally toggled in pairs, with each pair corresponding to a vertex attribute; if a pair is set, then vertices using this material will have the corresponding attribute. This is vital for reading geometry. | These flags are generally toggled in pairs, with each pair corresponding to a vertex attribute; if a pair is set, then vertices using this material will have the corresponding attribute. This is vital for reading geometry. Starting in Echoes, each pair is used to indicate the size of the attribute indices in the geometry data, with 3 meaning a 16-bit index and 2 meaning an 8-bit index. (This isn't actually used, though; the original game data always uses 16-bit indices.) | ||
GX supports up to 8 texture coords per vertex, but the game doesn't seem to allow you to assign more than 7 (though this could do with some double-checking). | |||
These are the possible attributes: | These are the possible attributes: | ||
Line 240: | Line 222: | ||
| Tex 2 | | Tex 2 | ||
|- | |- | ||
| | | 0xC000 | ||
| Tex 3 | | Tex 3 | ||
|- | |- | ||
| | | 0x30000 | ||
| Tex 4 | | Tex 4 | ||
|- | |- | ||
| | | 0xC0000 | ||
| Tex 5 | | Tex 5 | ||
|- | |- | ||
| | | 0x300000 | ||
| Tex 6 | | Tex 6 | ||
|} | |} | ||
Echoes introduces some new attributes using the top byte of the flags value; unlike the other flags, these are not set in pairs. Each individual bit indicates the presence of a different attribute. The indices in the geometry data are always 8 bits. | |||
{| class="wikitable" | |||
! Bit | |||
! Attribute | |||
|- | |||
| 0x1 | |||
| Position Matrix Index | |||
|- | |||
| 0x2 | |||
| Tex0 Matrix Index | |||
|- | |||
| 0x4 | |||
| Tex1 Matrix Index | |||
|- | |||
| 0x8 | |||
| Tex2 Matrix Index | |||
|- | |||
| 0x10 | |||
| Tex3 Matrix Index | |||
|- | |||
| 0x20 | |||
| Tex4 Matrix Index | |||
|- | |||
| 0x40 | |||
| Tex5 Matrix Index | |||
|- | |||
| 0x80 | |||
| Tex6 Matrix Index | |||
|} | |||
==== Group Index ==== | |||
The group index marks groups of materials that all have the same settings, but different textures. The game will check the value after loading the textures (but prior to the vertex attribute flags), and check whether the group index set on the material matches the material currently set up. If it does, it will skip the rest of the material setup. The value typically starts at 0 on the first material and increments by 1 on each new group with different settings. | |||
==== Konst Colors ==== | ==== Konst Colors ==== | ||
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==== Color Channels ==== | ==== Color Channels ==== | ||
There's | The color channels data consists of a count value indicating the number of color channels, and then one set of flags that controls the COLOR0 channel. The flags correspond to arguments passed to [http://libogc.devkitpro.org/gx_8h.html#a87d79cf2375217d06237c887ba027cc2 GX_SetChanCtrl()]. These are the settings: | ||
{| class="wikitable" | |||
! Bits | |||
! Hex | |||
! Description | |||
|- | |||
| 0 | |||
| 0x1 | |||
| '''Enable lighting''' (enable) | |||
|- | |||
| 1 | |||
| 0x2 | |||
| '''Ambient color source''' (ambsrc) | |||
|- | |||
| 2 | |||
| 0x4 | |||
| '''Material color source''' (matsrc) | |||
|- | |||
| 3-10 | |||
| 0x7F8 | |||
| '''Light mask'''; always 0, filled in at runtime ([http://libogc.devkitpro.org/group__lightid.html litmask]) | |||
|- | |||
| 11-12 | |||
| 0x1800 | |||
| '''Diffuse function''' ([http://libogc.devkitpro.org/group__difffn.html diff_fn]) | |||
|- | |||
| 13-14 | |||
| 0x6000 | |||
| '''Attenuation function''' ([http://libogc.devkitpro.org/group__attenfunc.html attn_fn]) | |||
|} | |||
There's only one set of flags, which operates on COLOR0. COLOR1 is reserved for dynamic shadows (terrain casting shadows on actors), so its settings can't be directly modified. Here's how the other color channel settings work. | |||
COLOR1A1's settings vary depending on whether shadowmaps are enabled: | |||
* No processing will be done if the count value is 0. Otherwise, the count value is ignored; the game will always set up both color channels. | |||
* COLOR1A1's ambient color is black, and its material color is white. | |||
* COLOR1 will use the diffuse function GX_DF_CLAMP and the attenuation function GX_AF_SPOT. It will have lighting disabled entirely if there are no lights in range | |||
If shadowmaps are disabled: | |||
* COLOR1 is disabled if the count value is not 2. If it is 2, then its ambient color will be black and its material color will be white. | |||
COLOR0 is set up the same way either way: | |||
* COLOR0 will use the flags from the material, with the light mask merged in. It will also have lighting disabled if there are no lights in range. | |||
* If there are no lights in range, COLOR0A0 will have its material color set to match its ambient color. Otherwise, its material color will be set to white. | |||
Finally, an important note is that the formatting of the color channel info is bugged. There is always a color channel count and a single set of flags; 8 bytes total. However, for some reason the game is expecting one set of flags per color channel. To reach the TEV stages, you need to advance (4 * count) bytes past the count value, rather than 4. A likely explanation is that there was one set of flags per channel earlier in development, and the material loading code wasn't fully updated when this was changed. It's not normally an issue because the count is always 1 in every file the game uses, but beware for experimentation/custom materials. | |||
=== TEV Stages === | === TEV Stages === | ||
Line 325: | Line 391: | ||
| 0x11 | | 0x11 | ||
| 1 | | 1 | ||
| '''Konst Alpha Input''' | | '''Konst Alpha Input''' ([http://libogc.devkitpro.org/group__tevkalphasel.html possible values]) | ||
|- | |- | ||
| 0x12 | | 0x12 | ||
| 1 | | 1 | ||
| '''Konst Color Input''' | | '''Konst Color Input''' ([http://libogc.devkitpro.org/group__tevkcolorsel.html possible values]) | ||
|- | |- | ||
| 0x13 | | 0x13 | ||
| 1 | | 1 | ||
| '''Rasterized Color Input''' | | '''Rasterized Color Input''' ([http://libogc.devkitpro.org/group__channelid.html possible values]) | ||
|- | |- | ||
| 0x14 | | 0x14 | ||
Line 578: | Line 644: | ||
=== UV Animations === | === UV Animations === | ||
The UV animations section immediately follows the texgen flags. | '' See [[UV Animations]]'' | ||
The UV animations section immediately follows the texgen flags. Its purpose is to generate texture matrices and post-transform matrices, which are then used to transform UV coordinates. This is commonly used to animate textures via simple UV scrolls, but it's also often used to simulate reflective surfaces that move with the camera. Materials can have multiple UV animations; in that case, each animation generates a separate texture/post-transform matrix and are loaded into GX sequentially. Texgen is used to set which matrices are used by which UV coordinates (if any). | |||
The section starts with this short header: | |||
{| class="wikitable" | {| class="wikitable" | ||
Line 594: | Line 664: | ||
|} | |} | ||
For info on how to read the animation data and how each animation mode works, see [[UV Animations]]. | |||
For | |||
[[Category:File Formats]] | [[Category:File Formats]] | ||
[[Category:Metroid Prime]] | [[Category:Metroid Prime]] | ||
[[Category:Metroid Prime 2: Echoes]] | [[Category:Metroid Prime 2: Echoes]] |