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- White is producing a 100% sun specular strength (glossy shiny)
- Black is producing a 0% sun specular strength (totally matte with no sun)
- Create a specific Layer Group to host all parts of the mask composing the Specular Map. This does give you total control on fine tuning the map during the various stage of the development and testing
- This is a GLOBAL map, not linked to specific liveries/skins, so it needs to host only common parts
- Follow the Carbody Shader guidelines for that specific task; (Part 2 of this document)
- Save the specular map in DXT5/BC3
Part 2 - Body Shader
Basic Terminology
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and practices
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Reflection Map; a raster image (image, texture and/or alpha channel in a texture) which is used to drive specific pixel information to the shaders. This kind of maps should not have any overbaked shading, baked ambient occlusion etc. because each pixel color it’s being used by the shader to render a material reflectivity, and the baking it’s affecting the correctness of the material simulation (see Pict. 1a). Car Normal maps, Reflection maps and also Specular maps (with some exceptions) are in fact more Data than art. From this concept depends the 70/80% of the final quality of the simulated material so they are an aspect to care about, especially to achieve constancy in the material simulation. For these reasons, most of the time, cars reflection maps, should be just a gray-scaled set of flat colored islands and masks, describing the various section of the main car body livery (see Pict. 1b). Also no dark areas (background) should be present between the different islands, because this could be a source of jaggies for lower MIPs, especially when not enough edge padding has been rendered around the UV map islands. Because of that, always use a flat colored canvas and then mask the areas you want to be different from the main color, in terms of pure cubemap lerp (reflectivity). Example: High Gloss body; All flat white, no UV islands, and masks for those bits you want to be less reflective. It’s also important to avoid dark reflection maps for high gloss bodies, as this means overdoing with multipliers in the Fresnel section. It’s always better to keep the higher values at the top of the chain (maps), and then use multipliers and final shader settings, to control and fine tune the final output. If we start from dark maps we’ll be forced to use too high multipliers and exponentials which usually it’s the main cause for dull looking car bodies other than a possible cause of jaggies because of the clamped output.
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- Specular Color: Is the color of the reflected light. For a glossy car body, this should be white in the range of (200,200,200) and (180,180,180). This is technically a pure albedo number, so never exceed the (200,200,200) to avoid producing more energy than the one hitting the surface. Darkest colors are describing Non-Gloss surfaces, or dirty parts if needed.
- Specular Power: this value does control the sun reflection spot power. Higher numbers will result in a tight and shiny spot, Lower numbers will soften the effect, producing wider and duller sun spots. High Gloss materials should be in the range of 250/350, with very bright Pixels in the Spec Map. Never use dark maps and then pushing on Spec Fresnel to bring back some highlight. Always start from a proper amount of power in the maps (brightness) and then control with Fresnel multipliers, not the opposite. Always remember the correct output starts from correct maps.
- Specular Fresnel Minimum: this is defining the “base” amount of the sun reflection strength. For Hi Gloss surfaces (bright pixels in the Spec map) should be set between 0.01 and 0.05, if using a white base in the ref/spec maps. Be careful with this number as may easily produce clipped pixels outside the Tonemapper capabilities (clamped white spots).
- Specular Fresnel Max (Fresnel Intensity): from 1 to 4, depending on the material (vinyl to glossy coat). A range from 3 to 3.5 it’s usually ideal for high gloss (based on white ref map)
- Specular Fresnel Exponential: Should be 5 as per equation
- Reflection Fresnel Minimum: from 0.01 to 0.1. This is controlling the final reflectance (based on white ref map). A range from 0.08 to 0.1 for hi gloss (based on white refmaps)
- Reflection Fresnel Max (Fresnel Intensity): Max 0.1 for realistic looking car bodies. More than this number, will start making them “milky”.
- Reflection Fresnel Exponential: Should be 5 as per equation.
Shader settings in 3D Studio Max
- Use Car body paint + damage + rain shader from gMotorMaterial list
- Assign textures as following :
- 1 : diffuse color ( texture map showing default paint when there is no skin loaded, alpha modulates reflections)
- 2 : damage map (this texture blends with diffuse based on local body damages)
- 3 : specular map (highlights, do not use fake AO, stay below 190 190 190 grey RGB value)
- 4 : bump map (if needed, normal map overriding 3D normals. If not needed use small flat 32x32 map)
- 5 : cube map (set as live mapper, see settings below)
- 6 : damage bump map (this texture blends with bump map based on local body damages)
- 7 : this slot is used by rain fx on body, let default settings, just load a small 32x32 map so the slot doesn't stay empty.
Main settings for WCCARBODY material using Car body paint + damage + rain shader :
Cube map settings :