Add comments on default depth buffers.

h3d/impl/DirectXDriver.hx

@@ -184,6 +184,7 @@ class DirectXDriver extends h3d.impl.Driver {
 		shaderVersion = if( version < 10 ) "3_0" else if( version < 11 ) "4_0" else "5_0";
 
 		Driver.iaSetPrimitiveTopology(TriangleList);
+		// Create a default depth buffer to mimic opengl.
 		defaultDepthInst = new h3d.mat.Texture(-1, -1, Depth24Stencil8);
 		defaultDepthInst.name = "defaultDepth";
 		for( i in 0...VIEWPORTS_ELTS )
@@ -321,6 +322,7 @@ class DirectXDriver extends h3d.impl.Driver {
 	}
 
 	override function getDefaultDepthBuffer():h3d.mat.Texture {
+		// Create an extra depth buffer to fit opengl default frame buffer.
 		if( extraDepthInst == null ) @:privateAccess {
 			extraDepthInst = new h3d.mat.Texture(0, 0, Depth24Stencil8);
 			extraDepthInst.name = "extraDepth";

h3d/impl/GlDriver.hx

@@ -1049,9 +1049,11 @@ class GlDriver extends Driver {
 	var defaultDepth : h3d.mat.Texture;
 
 	override function getDefaultDepthBuffer() : h3d.mat.Texture {
+		// Unfortunately there is no way to bind the depth buffer of the default frame buffer to a frame buffer object.
 		if( defaultDepth != null )
 			return defaultDepth;
 		defaultDepth = new h3d.mat.Texture(0, 0, Depth24Stencil8);
+		defaultDepth.name = "defaultDepthBuffer";
 		@:privateAccess {
 			defaultDepth.width = this.bufferWidth;
 			defaultDepth.height = this.bufferHeight;