GLSL built-in variables gl_Vertex, gl_Normal, gl_MultiTexCoord0 (version 130 까지만 지원)
GLSL Tutorial https://www.opengl.org/sdk/docs/tutorials/TyphoonLabs/Chapter_3.pdf
Light & Material를 사용하여 glutTeapot, glutSolidSphere, glutSolidCylinder를 Shading
Light & Material & Texture를 사용하여 glutTeapot, gluSphere, gluCylinder를 Shading
