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This rollout controls the Diffuse color of the Volumetric Shader. The Smoke Color can be a uniform color, a mixture of colors dragged by the simulation (RGB), a function of any physical channel, or sampled from a texture. It is also affected by lights and shadows cast by objects in the scene.
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In the volume shader, there are two types of content
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— diffuse and emissive. For simplicity's sake, we call the diffuse content
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Smoke
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and the emissive content
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Fire
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.
Diffuse (Smoke) needs external light in order to become visible, and also casts shadows.
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On the other hand, emissive (Fire) is visible even without being lit by lights
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. It also ignores their illumination, and does not cast shadows on itself.
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In addition, Phoenix has different tools that help you gain more to control over how the emissive fire illuminates the smoke and the scene - see the Create Fire Lights section sub-rollout for more details.Both |
Fire and smoke
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also have their own
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Color and Alpha. Alpha is a synonym for opacity, and transparency is the opposite of opacity
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. The Smoke Color, Smoke Opacity, as well as the Fire's Color and Opacity, can be mapped to a physical
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Grid Channel from the simulation, using the Based on parameter.
The Based on parameter specifies the source channel that will be rendered, and is set independently for the Fire, Smoke Color, and Smoke Opacity respectively. This makes shading very flexible, so that you can even render a simulation's fire as smoke, and smoke as fire, depending on the channel you set the Based on parameter to for each.
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Fire, Smoke Color, and Smoke Opacity, can also be Color gradients are used to remap a physical channel to render color, and the diagrams (also called ramps or curves) are used to remap a physical channel to render opacity or intensity.Also, each of them can be mapped to a texture, or to a grid channel Grid Channel multiplied by a texture, to achieve a wide variety of different results. Textures have infinite resolution, and so they can increase the detail above the resolution of the grid; , meaning that even with a low resolution simulation, you can get a detailed result when using a texture. By default, textures are static in space, but using TexUVW they . However, if you export the Grid Texture UVW Channel and use the TexUVW feature, textures can move together with the fluid .When there are both diffuse and emissive (smoke and fire) in the same voxel, there are 3 ways to determine the resulting color and alpha in that voxel - see the Fire Opacity Mode optionto create even more possibilities, such as melting textured icing on a cake. |
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UI Path: ||Select PhoenixFDSim|| > Attribute Editor > Rendering rollout > Smoke Color rollout |
Parameters
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When there is both Smoke and Fire (diffuse and emissive) in the same voxel, you can use the Fire Opacity Mode in the Fire sub-rollout to determine the resulting color and alpha. The Fire can simply use the opacity that is set for the smoke in the Smoke Opacity sub-rollout, or you can separate their opacities for additional control, using either the Fully Visible or Use Own Opacity modes. |
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Using the Based on parameter below, you can achieve a wide variety of results when shading Fire & Smoke. For example, the Fire (emissive content) is by default based on the Temperature Grid Channel. If instead it were based on Smoke Grid Channel data, then voxels containing Smoke values would be shaded as emissive (Fire). In other words, the Smoke would be rendered as Fire. On the other hand, if the Smoke Color (diffuse) & Smoke Opacity were based on Temperature, then voxels with Temperature values would be shaded as diffuse volumetrics (Smoke Color & Opacity). In other words, the Fire would be rendered as Smoke. |
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Based on | difSource – Specifies the source channel that will be used to determine the smoke color. By default, a uniform simple color set by the Constant Color option is used. This could also be a texture map, or read from the cache files - in that case the corresponding grid channel must be enabled from the Output rollout before the simulation is run.
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