Exhibit #0: Getting Info about Vertex Attributes

Vertex Attributes

What We Did

• You can get the number of vertex attributes that are used with gl.getProgramParameter(program, gl.ACTIVE_ATTRIBUTES).
  • The GLSL compiler will not include attributes that are declared but not used in your program.
• You can get info about an attribute with gl.getActiveAttrib(program, <index-of-the-attribute>)
  • Index goes from 0 to gl.getProgramParameter(program, gl.ACTIVE_ATTRIBUTES)-1
  • You get an object that contains the name, size (always 1), and type of the attribute.
• You can get the index of an attribute with the given name with gl.getAttribLocation(program, <attribute-name>)
• Important: You need to check whether an attribute exist before enabling or binding something to it.
• Hint: Use these commands to build better abstractions around vertex attributes.