iOS Developer Library — Prerelease


GLKit Framework Reference GLKNamedEffect Protocol Reference

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Objects that implement the GLKNamedEffect protocol provide rendering support to shader-based apps. An effect is expected to provide access to one or more shaders. The typical usage pattern for an effect separates initialization tasks from rendering tasks, allowing the effect object to be used efficiently inside an animation loop.

At initialization time, your app first creates a compatible context and makes it current. Then it allocates and initializes a new effect object, configures its properties, and calls its prepareToDraw method. Preparing an effect causes a shader to be compiled and bound to the current context. When an effect requires vertex data to act as inputs to the shader, your app also creates one or more vertex array objects. For each attribute required by the shader, the vertex array object should enable the attribute and point to data stored in a vertex buffer object.

At runtime, your app calls the effect’s prepareToDraw method to bind the shader program as the current program. Then, it binds a vertex array object (if necessary) and submits one or more OpenGL drawing commands.

  • Prepares an effect for OpenGL ES rendering.



    func prepareToDraw()


    - (void)prepareToDraw


    An effect binds a compiled shader program to the context and returns. Many effects also bind data to other OpenGL state variables—see the appropriate reference for each effect class.


    Available in iOS 5.0 and later.