_getComputeCacheKey( computeNode, stageCompute ) {

		return computeNode.id + ',' + stageCompute.id;

	}
Computes a cache key representing a compute pipeline.

@private
@param {Node} computeNode - The compute node.
@param {ProgrammableStage} stageCompute - The programmable stage representing the compute shader.
@return {string} The cache key.