Input variables

Output variables

• vec4 gl_Position : vertex homogeneous coordinates in projection space
• float gl_PointSize : using rendering points, size of the point

Input variables

• vec4 gl_FragCoord : pixel coordinates (x,y) + fragment depth (z)
• bool gl_FrontFacing : is pixel facing the camera or the opposite direction? (used in two-sided lighting)
• vec2 gl_PointCoord : when using Point Sprites, position within the point

Output variables

• vec4 gl_FragColor : RGBA color to use
• vec4 gl_FragData[gl_MaxDrawBuffers] : alternative to gl_FragColor when drawing to multiple buffers