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nintendo_64:fog [2018/07/01 21:49] David created |
nintendo_64:fog [2019/05/29 20:49] (current) David Updated dead link |
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| - | Fog alters the color of polygons based on their distance from the camera. As objects and geometry get farther away from the camera, they start to blend into the background color. This is an easy and useful method to reduce the strain on the N64's RCP, and can improve performance. | + | **Vertex Fog** is a setting in the RSP that can be used to fade polygons into the background. It works by gradually blending the fog color (or transparency) into the geometry until it looks like it completely faded away. This effect can be used along with lowering the draw distance to reduce lag. |
| - | If your level still has lag even with fog enabled, try cutting down the amount of polygons and active objects on screen. | + | Do note that you cannot use vertex alpha when fog is enabled. This is because when the SHADE alpha value is used in the color combiner, it will get the fog alpha instead of the vertex alpha. |
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| ===== Setting Fog Color ===== | ===== Setting Fog Color ===== | ||
| - | The fog color is a simple RGBA value that you define in the display list: | + | The fog color is a simple RGBA value that you define in the display list. Generally, this should be the same color as the background. If the background is complicated (clouds, mountains, gradients, etc), [[http://ultra64.ca/files/documentation/online-manuals/man/pro-man/pro11/index11.8.html|then you should try making the objects fade by transparency rather than by color]]. |
| Fast3D / Fast3DEX / Fast3DEX2 / Fast3DZEX | Fast3D / Fast3DEX / Fast3DEX2 / Fast3DZEX | ||
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| ---- | ---- | ||
| - | ===== Vertex Alpha & Fog ===== | + | ===== Disabling Fog ===== |
| - | > From the N64 Function Reference Manual for **gDPSetFogColor**: | + | |
| - | > N64 processes fog by Gouraud-shading the fog attenuation coefficients in the alpha channel of RDP. At that time, the BL adjusts the attenuation of the pipeline pixel colors to the surrounding fog color. Because the alpha channel of RDP is being used for Gouraud-shading the fog attenuation coefficient, normal alpha values cannot be Gouraud-shaded. **In other words, you cannot change the transparency inside a single triangle when you are using fog.** | + | |
| - | What this says is that you cannot use vertex alpha transparency while fog is enabled. Fog is independent of lighting and textures, so you can still use the alpha transparency from those sources. | + | To disable fog, you simply have to do the reverse of what you did to enable it. This can vary based on what the default settings are in each game. For custom Super Mario 64 levels, we do the following: |
| - | ---- | + | 1.) Set the RDP back into 1 cycle mode. |
| - | ===== Background Images & Fog ===== | + | Fast3D / Fast3DEX |
| + | BA 00 14 02 00 00 00 00 | ||
| - | Because of how fog works, using a background that is not a solid color will make the fog look weird. It is best to use a solid color that matches the fog color. | + | Fast3DEX2 / Fast3DZEX |
| + | E3 00 14 02 00 00 00 00 | ||
| - | If you are making or modifying a level in Super Mario 64, then you can change the background to a solid color by modifying the [[super_mario_64:geometry_layout_commands#set_background|0x19 command in the level's geometry layout]]. | + | C/C++ |
| + | gsDPSetCycleType(G_CYC_1CYCLE) | ||
| + | |||
| + | |||
| + | 2.) Next we set the render mode back to normal. (see: http://n64devkit.square7.ch/n64man/gdp/gDPSetRenderMode.htm) | ||
| + | |||
| + | Fast3D / Fast3DEX | ||
| + | B9 00 03 1D 00 44 30 78 | ||
| + | |||
| + | Fast3DEX2 / Fast3DZEX | ||
| + | E2 00 03 1D 00 44 30 78 | ||
| + | |||
| + | C/C++ | ||
| + | gsDPSetRenderMode(G_RM_AA_ZB_OPA_SURF, G_RM_NOOP2) // If surface is fully opaque | ||
| + | gsDPSetRenderMode(G_RM_AA_ZB_XLU_SURF, G_RM_NOOP2) // If surface has transparency | ||
| + | |||
| + | 3.) Finally we clear the fog flag in the geometry mode. | ||
| + | Fast3D / Fast3DEX | ||
| + | B6 00 00 00 00 01 00 00 | ||
| + | |||
| + | Fast3DEX2 / Fast3DZEX | ||
| + | D9 01 00 00 00 00 00 00 | ||
| + | |||
| + | C/C++ | ||
| + | gsSPClearGeometryMode(G_FOG) | ||
| ---- | ---- | ||
| ===== References ===== | ===== References ===== | ||
| - | * https://level42.ca/projects/ultra64/Documentation/man/pro-man/pro11/index11.8.html | + | * http://ultra64.ca/files/documentation/online-manuals/man/pro-man/pro11/index11.8.html |
| * http://ultra64.ca/files/documentation/online-manuals/man/n64man/gdp/gDPSetFogColor.html | * http://ultra64.ca/files/documentation/online-manuals/man/n64man/gdp/gDPSetFogColor.html | ||
| * http://n64devkit.square7.ch/n64man/gdp/gDPSetRenderMode.htm | * http://n64devkit.square7.ch/n64man/gdp/gDPSetRenderMode.htm | ||
nintendo_64/fog.1530481794.txt.gz · Last modified: 2018/07/01 21:49 by David