Update README.md

README.md

@@ -9,3 +9,31 @@
 # opengl
 
 An OpenGL function loader written in pure swift. To use it, `import OpenGL` in your swift file.
+
+*OpenGL* is a function loader which allows you to call OpenGL GPU functions from swift programs. These functions are loaded lazily at runtime by *OpenGL*. *OpenGL* also diagnoses invalid OpenGL function calls due to the function not being available on a particular GPU and OpenGL version.
+
+*OpenGL* provides access to OpenGL functions both with labeled and unlabeled arguments. This can help you avoid common argument ordering bugs.
+
+```swift
+var tex_id:UInt32 = 0
+glGenTextures(1, &tex_id)
+glBindTexture(GL_TEXTURE_2D, tex_id)
+glTexImage2D(target         : GL_TEXTURE_2D,
+             level          : 0,
+             internalformat : GL_RGBA8,
+             width          : h,
+             height         : k,
+             border         : 0,
+             format         : GL_RGBA,
+             type           : GL_UNSIGNED_BYTE,
+             pixels         : pixbuf)
+glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE)
+glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE)
+```
+
+*OpenGL* also provides typealias definitions for OpenGL types.
+
+```swift
+let tex_id1:GLuint
+let tex_id2:UInt32
+```