added OSL language

Added most of the basics

osl.html.markdown

@@ -0,0 +1,138 @@
+---
+language: osl
+filename: learnosl.osl
+contributors:
+  - ["Preetham Pemmasani", "https://github.com/Preetham-ai"]
+---
+
+OSL (Open Shading Language) is a programming language designed for creating shaders to describe how surfaces react to light in computer graphics.
+
+[Read more here.](https://raw.githubusercontent.com/imageworks/OpenShadingLanguage/master/src/doc/osl-languagespec.pdf)
+
+```c
+
+
+// Single-line comments start with //
+
+/* Multi line comments are preserved. */
+
+// Statements can be terminated by ;
+dothis();
+
+///////////////
+// 1. Basics //
+///////////////
+ 
+float num = 3.00;  // Scalar floating-point data (numbers)
+int num = 3; // Integer data
+
+// Math works as you would expect
+3 + 1;   // 4
+74 - 3;   // 71
+20 * 2; // 40
+75/3;  // 25.0
+
+// And modulo division only works with integers
+10 % 2; // 0
+31 % 4; // 1
+
+// Bitwise operations only works with integers
+- 0 // 1 (Negation)
+~ 00100011 // 11011100 (bitwise Compliment)
+1 << 2; // 4 (shift Left)
+12 >> 1; // 3 (shift Right)
+1 & 0; // 0 (bitwise AND)
+1 | 0; // 1 (bitwise OR)
+1 ^ 1; // 0 (bitwise XOR)
+
+// We also have booleans
+true;
+false;
+
+// Negation uses the ~ symbol
+~true; // false
+~false; // true
+
+// Relation Operators are defined like:
+0 == 0 // true (equal to)
+0 != 1 // true (not equal to)
+5 < 3 // false (less then)
+3 <= 3 // true (less than or equal to)
+69 > 69 // false (greater than)
+99 >= 52 // true (greater than or equal)
+
+
+// Functions are same as C and C++
+float sum(float a, float b){
+	return a+b;
+}
+
+int subtract(int a, int b){
+	return a-b;
+}
+
+sum(2,3); // 5
+
+// Shader (similar to main function in C)
+// The inputs should be initialized
+shader multiply(float a = 0.0, float b = 0.0, output float c = 0.0){
+    c = a*b;
+}
+
+// Functions can be used inside shader.
+
+/////////////////////////
+// 2. Global Variables //
+/////////////////////////
+
+// Contains information that the renderer knows about the point being shaded
+//These variables need not be declared
+
+point P // Position of the point you are shading
+vector I // Incident ray direction from viewing position to shading position
+normal N
+normal Ng
+float u
+float v
+vector dPdu
+vector dPdv
+point Ps
+float time 
+float dtime
+vector dPdtime
+closure color Ci
+
+/////////////////////
+// 4. Control flow //
+/////////////////////
+
+// Conditionals in OSL are just like in C or C++.
+
+// If/Else
+if (5>2){
+	x = s;
+	l = x;
+}
+else{
+	x = s + l; 
+}
+
+// 'while' loop
+int i = 0;
+while (i < 5) {
+    i += 1;
+    printf("Current value of i: %d\n", i);
+}
+
+// 'do-while' loop is where test happens after the body of the loop
+int i = 0;
+do {
+    printf("Current value of i: %d\n", i);
+    i += 1;
+} while (i < 5);
+
+// 'for' loop
+for (int i = 0; i < 5; i += 1) {
+    printf("Current value of i: %d\n", i);
+}
+```