1/3/2023 0 Comments Renderman shader language![]() Shading Language VariablesGlobal variablesgraphics state variables type variablename Static 1D arrays are allowede.g.)float a uniform float b float c = 1 float d = b*a float e Shading Language data typeBuilt-in typesFloatsColorsPoints, Vectors, NormalsMatricesStringsSL has no double or int typesSL does not support user-defined structures or pointer of any kind Types of shadersSurface shadersAppearance of surfaceHow they react to the lightsDisplacement shadersHow wrinkle or bumpLight shadersDirections, amounts, and colors of illuminationVolume shadersHow light is affected as it passes through a participating mediumImager shadersDescribe color transformation make to final pixel values before the are output Specular ReflectionPhong Modelcos (a)n : This is a physically-motivated hack!Īmbient TermRepresents reflection of all indirect illuminationThis is a total hackAvoid complexity of global illumination Specular ReflectionReflection is strongest near mirror angleExamples: mirrors, metals Parameterized shading modelPhong illumination modelĭoes not change the fundamental form of the shading equationNarrow range of appearancesSimple analytic model:Diffuse reflection +Specular reflection +Emission +Ambientĭiffuse ReflectionAssume surface reflects equally in all directionsExample: chalk, clayĭiffuse ReflectionLambertian modelCosine law (dot product) Weimer1980, Shading dispatch tableRobert Cook1984, Shade TreesKen Perlin1985, Pixel StreamPat Hanrahan & Jim Lawson1990, Shading Language New Shading SystemTurner Whitted & David M. ![]() Conventional Shading SystemFixed parameter shading systemDisadvantagesBuilt-in shading model is NOT enoughNew shading modelRealistic shading modelNPRCan be inefficientFlexible, extensible system is needed ![]()
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