Render-Target.md

Render targets can be used to capture a scene to a Texture which can be used later.

Render targets for 3d scenes require both a texture to write to, and a depth buffer. Additionally, you must pass the Target flag to the texture during creation.

var renderTarget = new Texture( engine.width, engine.height, [ Target ] );
renderTarget.depthBuffer = new DepthBuffer( engine.width, engine.height );

Rendering a scene to texture

To render our scene, we can use pushTarget and popTarget to change what surface we render to. pushTarget will push a new render target on to the render stack. popTarget will remove the topmost target. This allows you to nest render operations as needed. You can also use pushTargets if you wish to render to multiple textures.

engine.pushTarget(renderTarget);

engine.clear(0, 1); // Clears the render target texture and depth buffer
s3d.render(e);

engine.popTarget();

Displaying a render texture in 2d

To display a render texture result in a 2d context, you can simply create a Tile out of the render texture. This will update automatically, as the bitmap will continue to reference the underlying texture. It can then be used as a Bitmap or in any other place Tiles are used.

var renderTargetBitmap = new Bitmap(Tile.fromTexture(renderTarget), s2d);

Displaying a render texture in 3d

This example will require a second scene. One which we'll render to a texture, and another which we will display it in.

override function init() {
	renderTarget = new Texture(engine.width,engine.height, [ Target ]);
	renderTarget.depthBuffer = new DepthBuffer(engine.width, engine.height);

	s3dTarget = new h3d.scene.Scene();

	// The object we're going to display in our scene
	var prim = h3d.prim.Cube.defaultUnitCube();
	var mat = h3d.mat.Material.create(renderTarget);
	obj1 = new h3d.scene.Mesh(prim, mat, s3d);

	// The object we're going to capture in our Render Target
	obj2 = cache.loadModel(hxd.Res.mdl.test2);

	s3dTarget.addChild(obj2);
}

override function render(e:h3d.Engine) {
	// Render the target first
	engine.pushTarget(renderTarget);

	engine.clear(0, 1);
	s3dTarget.render(e);

	engine.popTarget();

	// Now render our scene
	s3d.render(e);

	s2d.render(e);
}