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Update osl.html.markdown
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Preetham Pemmasani
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@ -17,14 +17,16 @@ OSL (Open Shading Language) is a programming language designed for creating shad
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/* Multi line comments are preserved. */
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// Statements can be terminated by ;
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dothis();
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divide(1,2);
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///////////////
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// 1. Basics //
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///////////////
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float num = 3.00; // Scalar floating-point data (numbers)
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int num = 3; // Integer data
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// Declating variables
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float Num = 3.00; // Scalar floating-point data (numbers)
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int _num = 3; // Integer data
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float c[3] = {0.1, 0.2, 3.14}; // Array
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// Math works as you would expect
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3 + 1; // 4
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@ -37,7 +39,7 @@ int num = 3; // Integer data
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31 % 4; // 1
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// Bitwise operations only works with integers
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- 0 // 1 (Negation)
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- 0 // 1 (Unary Negation)
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~ 00100011 // 11011100 (bitwise Compliment)
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1 << 2; // 4 (shift Left)
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12 >> 1; // 3 (shift Right)
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@ -49,9 +51,15 @@ int num = 3; // Integer data
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true;
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false;
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// Negation uses the ~ symbol
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~true; // false
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~false; // true
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// Booleans can't be compared to integers
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true = 1 // Error
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false = 0 // Error
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// Negation uses the ! symbol
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!0; // 1
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!1; // 0
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!2; // 0
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//... and so on
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// Relation Operators are defined like:
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0 == 0 // true (equal to)
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@ -73,34 +81,132 @@ int subtract(int a, int b){
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sum(2,3); // 5
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// Shader (similar to main function in C)
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// The inputs should be initialized
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shader multiply(float a = 0.0, float b = 0.0, output float c = 0.0){
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////////////////
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// 2. Shaders //
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////////////////
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// Shaders extend the functionality of a renderer with custom behavior of materials and light
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// Shader's syntax is similar to the main function in C
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// The inputs and the outputs should be initialized to default types
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shader multiply(float a = 0.0,
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float b = 0.0,
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output float c = 0.0){
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c = a*b;
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}
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// Functions can be used inside shader.
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// Double brackets[[ ]] is used to classify metadata of a shader
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surface plastic
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[[ string help = "Realistic wood shader" ]]
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(
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color Plastic = color (0.7, 0.5, 0.3) [[ string help = "Base color" ]],
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float Reflectivity = 0.5 [[ float min = 0, float max = 1 ]],
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){...}
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/////////////////////////
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// 2. Global Variables //
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/////////////////////////
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///////////////////////////////////////
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// Metadata Types
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///////////////////////////////////////
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// Contains information that the renderer knows about the point being shaded
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//These variables need not be declared
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[[ string label = "IOR" ]] // Display-name in UI of the parameter
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[[ string help = "Change Refractive Index" ]] // Info about the parameter
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[[ string help = "widget" // Gives widgets to input the parameter
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string widget = "number" ]] // input float or int
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string widget = "string" ]] // String input
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string widget = "boolean" ]] // yes/no (or) 1/0
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string widget = "popup", options = "smooth|rough" ]] // Drop-down list
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// enum Drop-down list can also be made
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string widget = "mapper", options = "smooth:0|rough:1" ]]
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string widget = "filename" ]] // Input files externally
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string widget = "null" ]] // null input
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[[ float min = 0.0 ]] // Minimum value of parameter
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[[ float max = 0.5 ]] // Maximum value of parameter
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[[ int slider = 3.0 // Adds a slider as an input
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int slidermin = -1]] // minimum value of the slider
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int slidermax = 3]] // maximum value of the slider
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int slidercenter = 2]] // origin value of the slider
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[[ float sensitivity = 0.5 ]] // step size for incrementing the parameter
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[[ string URL = www.example.com/ ]] // URL of shader's documentation
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// There are different types of shaders
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/* Surface shaders determine the basic material properties of a surface and
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how it reacts to light */
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// Light shaders are a type of SURFACE shaders used for emissive objects.
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// Displacement shaders alter the geometry using position and normals.
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// Volume shaders adds a medium like air/smoke/dust into the scene.
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volume multiply(float a = 0.0, float b = 0.0, output float c = 0.0){
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c = 2*a+b;
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}
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////////////////////////////////////////
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// 3. Data Types and Global Variables //
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////////////////////////////////////////
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// Data Types
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// 1. int (Integer)
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int x = -12; // Minimum size of 32-bits
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int new2 = 0x01cf // Hexadecimal can also be specified
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///////////////////////////////////////
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// Order of Evaluation
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///////////////////////////////////////
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// From top to bottom, top has higher precedence
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//-----------------------------------//
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// Operators //
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//-----------------------------------//
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// int++, int-- //
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// ++ int --int - ~ ! //
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// * / % //
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// + - //
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// << >> //
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// < <= > >= //
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// == != //
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// & //
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// ^ //
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// | //
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// && //
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// || //
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// ?: //
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// = += -= *= /= //
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//-----------------------------------//
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// 2. float (Floating-point number)
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float A = 2.3; // minimum IEEE 32-bit float
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float Z = -4.1e2
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// Order of evaluation is similar to int.
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// Operations like ( ~ ! % << >> ^ | & && || ) aren't available in float
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// 3. color (Red, Green, Blue)
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color p = color(0,0,0) // black
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color q = color(1) // white ( same as color(1,1,1) )
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color r = color("rgb", 0.23, 0.1, 0.8) // explicitly specify in RGB
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color s = color("hsv", 0.23, 0.1, 0.8) // specify in HSV
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// HSV stands for (Hue, Saturation, Luminance)
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// HSL stands for (Hue, Saturation, Lightness)
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// YIQ, XYZ and xyY formats can also be used
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// Global Variables
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// Contains info that the renderer knows
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// These variables need not be declared
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point P // Position of the point you are shading
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vector I // Incident ray direction from viewing position to shading position
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normal N
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normal Ng
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float u
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float v
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vector dPdu
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vector dPdv
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point Ps
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float time
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float dtime
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vector dPdtime
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closure color Ci
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normal N // Normal of the surface at P
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normal Ng // Normal of the surface at P irrespective of bump mapping
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float u // UV 2D x - parametric coordinate of geometry
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float v // UV 2D y - parametric coordinate of geometry
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vector dPdu // change of P with respect to u tangent to the surface
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vector dPdv // change of P with respect to v tangent to the surface
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float time // Current time
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float dtime // Time covered
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vector dPdtime // change of P with respect to time
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/////////////////////
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// 4. Control flow //
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@ -110,11 +216,11 @@ closure color Ci
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// If/Else
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if (5>2){
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x = s;
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l = x;
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int x = s;
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int l = x;
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}
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else{
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x = s + l;
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int x = s + l;
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}
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// 'while' loop
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