irrlicht/include/IMaterialRenderer.h

// Copyright (C) 2002-2007 Nikolaus Gebhardt
// This file is part of the "Irrlicht Engine".
// For conditions of distribution and use, see copyright notice in irrlicht.h

#ifndef __I_MATERIAL_RENDERER_H_INCLUDED__
#define __I_MATERIAL_RENDERER_H_INCLUDED__

#include "IReferenceCounted.h"
#include "SMaterial.h"
#include "S3DVertex.h"

namespace irr
{
namespace video  
{

class IVideoDriver;
class IMaterialRendererServices;

//!	Interface for material rendering. Can be used to extend the engine with new materials.
/** Refer to IVideoDriver::addMaterialRenderer() for more informations on how to extend the engine
 with new materials.
*/
class IMaterialRenderer : public virtual IReferenceCounted
{
public:

	//! destructor
	virtual ~IMaterialRenderer() {}

	//! Called by the IVideoDriver implementation the let the renderer set its needed render states. 
	/** This is called during the IVideoDriver::setMaterial() call.
	When overriding this, you can set some renderstates or for example a vertex or pixel shader
	if you like.
	\param material: The new material parameters to be set. The renderer may change the material
	flags in this material. For example if this material does not accept the zbuffer = true, it
	can set it to false. This is useful, because in the next lastMaterial will be just the material
	in this call.
	\param lastMaterial: The material parameters which have been set before this material.
	\param resetAllRenderstates: True if all renderstates should really be reset. This is usually
	true if the last rendering mode was not a usual 3d rendering mode, but for example 
	a 2d rendering mode.
	You should reset really all renderstates if this is true, no matter if the lastMaterial had
	some similar settings. This is used because in most cases, some common renderstates are not
	changed if they are already there, for example bilinear filtering, wireframe, gouraudshading, 
	lighting, zbuffer, zwriteenable, backfaceculling and fogenable.
	\param services: Interface providing some methods for changing advanced, internal
	states of a IVideoDriver. */
	virtual void OnSetMaterial(const SMaterial& material, const SMaterial& lastMaterial,
		bool resetAllRenderstates, IMaterialRendererServices* services) {};

	//! Called every time before a new bunch of geometry is being drawn using this material with
	//! for example drawIndexedTriangleList() call.
	/** OnSetMaterial should normally only be called if the renderer decides that the renderstates should be changed, it won't be called if for
	example two drawIndexedTriangleList() will be called with the same material set. This 
	method will be called every time. This is useful for example for materials with shaders,
	which don't only set new renderstates but also shader constants.
	\param service: Pointer to interface providing methos for setting constants and other things.
	\param vtxtype: Vertex type with which the next rendering will be done. This can be used
	by the material renderer to set some specific optimized shaders or if this is an incompatible
	vertex type for this renderer, to refuse rendering for example.
	\return Returns true if everything is ok, and false if nothing should be rendered. 
	The material renderer can choose to return false for example if he doesn't support the
	specified vertex type. This is actually done in D3D8 and D3D9 when using a 
	normal mapped material with a vertex type other than EVT_TANGENTS.  */
	virtual bool OnRender(IMaterialRendererServices* service, E_VERTEX_TYPE vtxtype) { return true; };

	//! Called by the IVideoDriver to unset this material.
	/** Called during the 
	IVideoDriver::setMaterial() call before the new material will get the OnSetMaterial()
	call. */
	virtual void OnUnsetMaterial() {}

	//! Returns if the material is transparent. 
	/** The scene managment needs to know this
	for being able to sort the materials by opaque and transparent. */
	virtual bool isTransparent() const { return false; }

	//! Returns the render capability of the material. 
	/** Because some more complex materials
	are implemented in multiple ways and need special hardware capabilities, it is possible
	to query how the current material renderer is performing on the current hardware with this
	function.
	\return Returns 0 if everything is running fine. Any other value is material renderer
	specific and means for example that the renderer switched back to a fall back material because 
	it cannot use the latest shaders. More specific examples: 
	Fixed function pipeline materials should return 0 in most cases, parallax mapped
	material will only return 0 when at least pixel shader 1.4 is available on that machine. */
	virtual s32 getRenderCapability() const { return 0; }
};


} // end namespace video
} // end namespace irr

#endif