Changelog:
1.0.8
* Improved energy conservation for Phong material
* Increased max albedo for phong and diffuse from 0.9 to 1.0
* added Oren Nayar material
* staticly linking with OpenEXR
* OpenEXR support enabled for windows 64-bit build
* added specular_reflectivity_spectrum option for the Phong material.
The specular reflectivity spectrum for Phong materials defines the specular reflectivity at normal incidence.
If this element is present, then diffuse will be set to zero.
The specular reflectivity spectrum can be used to create metal materials without using n-k data.
Use the specular reflectivity spectrum like this:
Code: Select all
<material>
<name>spheremat</name>
<phong>
<diffuse>0.0 0.0 0.0</diffuse>
<exponent>300</exponent>
<specular_reflectivity_spectrum>
<rgb>
<rgb>0.6 0.6 0.6</rgb>
<gamma>1</gamma>
</rgb>
</specular_reflectivity_spectrum>
</phong>
</material>
The Oren-Nayar BRDF models very rough surfaces, such as clay, the moon, sprayed concrete etc... It differs from a Lambertian BRDF in that it has more back-scattering.
The sigma parameter is a roughness parameter that controls the amount of back-scattering.
Oren nayar material:
Code: Select all
<material>
<name>3</name>
<oren_nayar>
<albedo_spectrum>
<uniform>
<value>0.7</value>
</uniform>
</albedo_spectrum>
<sigma>0.2</sigma>
</oren_nayar>
</material>
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