Overview

An SPRenderTexture is a dynamic texture on which you can draw any display object.

After creating a render texture, just call the drawObject: method to render an object directly onto the texture. The object will be drawn onto the texture at its current position, adhering its current rotation, scale and alpha properties.

Drawing is done very efficiently, as it is happening directly in graphics memory. After you have drawn objects on the texture, the performance will be just like that of a normal texture – no matter how many objects you have drawn.

If you draw lots of objects at once, it is recommended to bundle the drawing calls in a block via the bundleDrawCalls: method, like shown below. That will speed it up immensely, allowing you to draw hundreds of objects very quickly.

[renderTexture bundleDrawCalls:^
 {
     for (int i=0; i<numDrawings; ++i)
     {
        image.rotation = (2 * PI / numDrawings) * i;
        [renderTexture drawObject:image];            
     }             
 }]; 

One thing you should be aware of is that calling any of this class' drawing methods from within a render: method of an SPDisplayObject may lead to problems with texture bindings. To circumvent this, either move your drawing code into an enter frame event listener or call the reset method of SPRenderSupport after the drawing calls.