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specular_lys [2017/05/15 21:32] adavies |
specular_lys [2017/05/15 21:55] adavies [Reflected Beam] |
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| The top MIP level will always be used for a 100% sharp reflection (roughness 0.0) and the offset from the bottom MIP level specified using “MIP Offset” in the specular group determines where we have 100% blurriness (roughness 1.0). The default offset of 3 corresponds to MIP level 8x8. Checking “Coarse Irradiance” in the 3D Preview will enable using the MIP level at your chosen offset for diffuse lighting in the viewport. | The top MIP level will always be used for a 100% sharp reflection (roughness 0.0) and the offset from the bottom MIP level specified using “MIP Offset” in the specular group determines where we have 100% blurriness (roughness 1.0). The default offset of 3 corresponds to MIP level 8x8. Checking “Coarse Irradiance” in the 3D Preview will enable using the MIP level at your chosen offset for diffuse lighting in the viewport. | ||
| - | Note that our implementation of BurleyToMip() below differs from the more typical form as cube maps convolved in Lys are based on RdotL and not NdotH. However, the lit specular response resulting from the "roughness texture" will be the same as in other pbr based game engines and tools. | + | Note that our implementation of BurleyToMip() below differs from the more typical form as cube maps convolved in Lys are based on RdotL and not NdotH. You can find a more detailed description in [[specular_lys#pre-convolved_cube_maps_vs_path_tracers|Pre-convolved Cube Maps vs Path Tracers]]. |
| - | You can find a more detailed description in [[specular_lys#pre-convolved_cube_maps_vs_path_tracers|Pre-convolved Cube Maps vs Path Tracers]]. | + | Despite the difference in distribution of MIPs the lit specular response resulting from the generated “roughness texture” will be identical to other PBR based game engines and tools. |
| <code glsl>float BurleyToMip(float fPerceptualRoughness, int nMips, float NdotR) | <code glsl>float BurleyToMip(float fPerceptualRoughness, int nMips, float NdotR) | ||
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| ==== Reflected Beam ==== | ==== Reflected Beam ==== | ||
| - | [{{https://s3.amazonaws.com/docs.knaldtech.com/docuwiki/reflected_beam_new.png?nolink&1075 |The view direction v reflected by dH will result in dR. Given the existing symmetry the central direction r of dR will result in dV when reflected by dH.}}] | + | [{{https://s3.amazonaws.com/docs.knaldtech.com/docuwiki/reflected_beam_new.png?nolink&1075 |The view direction v reflected by dH will result in dR. Given the existing symmetry the central direction r of dR will result in dV when reflected by dH.}}]\\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ |
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| As an approximation we can correlate size of solid angle with "blur strength"and replace ''h_dot_r'' with ''n_dot_r''. So ultimately what we do is adjust our specular power in the following way: | As an approximation we can correlate size of solid angle with "blur strength"and replace ''h_dot_r'' with ''n_dot_r''. So ultimately what we do is adjust our specular power in the following way: | ||
specular_lys.txt · Last modified: 2017/05/23 03:49 (external edit)
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