/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright © 2000-2004 The OGRE Team
Also see acknowledgements in Readme.html

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.
-----------------------------------------------------------------------------
*/

#ifndef __TERRAINVERTEXPROGRAM_H__
#define __TERRAINVERTEXPROGRAM_H__

#include "OgrePrerequisites.h"
#include "OgreCommon.h"
#include "OgreString.h"

namespace Ogre {

    /*
    Static class containing the source to vertex programs used to 
    morph the terrain LOD levels. The programs are generated from 
    the following Cg:
    @code 	
    // No fog morphing terrain
    void terrain_vp(
	    float4 position : POSITION,
	    float2 uv1   	: TEXCOORD0,
	    float2 uv2	 	: TEXCOORD1,
	    float delta     : BLENDWEIGHT,

	    out float4 oPosition : POSITION,
	    out float2 oUv1		 : TEXCOORD0,
	    out float2 oUv2		 : TEXCOORD1,
	    out float4 colour    : COLOR,
	    uniform float4x4 worldViewProj,
	    uniform float morphFactor
	    )
    {
	    // Apply morph
	    position.y = position.y + (delta.x * morphFactor);
	    // world / view / projection
	    oPosition = mul(worldViewProj, position);
	    // Main texture coords
	    oUv1 = uv1;
	    // Detail texture coords
	    oUv2 = uv2;
	    // Full bright (no lighting)
	    colour = float4(1,1,1,1);
    }


    // Linear fogged morphing terrain
    void terrain_vp_linear(
	    float4 position : POSITION,
	    float2 uv1   	: TEXCOORD0,
	    float2 uv2	 	: TEXCOORD1,
	    float delta     : BLENDWEIGHT,

	    out float4 oPosition : POSITION,
	    out float2 oUv1		 : TEXCOORD0,
	    out float2 oUv2		 : TEXCOORD1,
	    out float4 colour    : COLOR,
	    out float fog		 : FOG,
	    uniform float4x4 worldViewProj,
	    uniform float morphFactor
	    )
    {
	    // Apply morph
	    position.y = position.y + (delta.x * morphFactor);
	    // world / view / projection
	    oPosition = mul(worldViewProj, position);
	    // Main texture coords
	    oUv1 = uv1;
	    // Detail texture coords
	    oUv2 = uv2;
	    // Full bright (no lighting)
	    colour = float4(1,1,1,1);
	    // Fog 
	    // f = end - camz / end - start
	    // when start / end has been set, fog value is distance
	    fog = oPosition.z;
    }


    // Exp fogged morphing terrain
    void terrain_vp_exp(
	    float4 position : POSITION,
	    float2 uv1   	: TEXCOORD0,
	    float2 uv2	 	: TEXCOORD1,
	    float delta     : BLENDWEIGHT,

	    out float4 oPosition : POSITION,
	    out float2 oUv1		 : TEXCOORD0,
	    out float2 oUv2		 : TEXCOORD1,
	    out float4 colour    : COLOR,
	    out float fog		 : FOG,
	    uniform float4x4 worldViewProj,
	    uniform float morphFactor,
	    uniform float fogDensity)
    {
	    // Apply morph
	    position.y = position.y + (delta.x * morphFactor);
	    // world / view / projection
	    oPosition = mul(worldViewProj, position);
	    // Main texture coords
	    oUv1 = uv1;
	    // Detail texture coords
	    oUv2 = uv2;
	    // Full bright (no lighting)
	    colour = float4(1,1,1,1);
	    // Fog 
	    // f = 1 / e ^ (camz x density)
	    // note pow = exp(src1 * log(src0)).
	    fog = 1 / (exp((oPosition.z * fogDensity) * log(2.718281828)));
    }


    // Exp2 fogged morphing terrain
    void terrain_vp_exp2(
	    float4 position : POSITION,
	    float2 uv1   	: TEXCOORD0,
	    float2 uv2	 	: TEXCOORD1,
	    float delta     : BLENDWEIGHT,

	    out float4 oPosition : POSITION,
	    out float2 oUv1		 : TEXCOORD0,
	    out float2 oUv2		 : TEXCOORD1,
	    out float4 colour    : COLOR,
	    out float fog		 : FOG,
	    uniform float4x4 worldViewProj,
	    uniform float morphFactor,
	    uniform float fogDensity)
    {
	    // Apply morph
	    position.y = position.y + (delta.x * morphFactor);
	    // world / view / projection
	    oPosition = mul(worldViewProj, position);
	    // Main texture coords
	    oUv1 = uv1;
	    // Detail texture coords
	    oUv2 = uv2;
	    // Full bright (no lighting)
	    colour = float4(1,1,1,1);
	    // Fog 
	    // f = 1 / e ^ (camz x density)^2
	    // note pow = exp(src1 * log(src0)).
	    float src1 = oPosition.z * 0.002;
	    fog = 1 / (exp((src1*src1) * log(2.718281828f)));
    }

    @endcode
    */
    class TerrainVertexProgram
    {
    private:
        static String mNoFogArbvp1;
        static String mLinearFogArbvp1;
        static String mExpFogArbvp1;
        static String mExp2FogArbvp1;

        static String mNoFogVs_1_1;
        static String mLinearFogVs_1_1;
        static String mExpFogVs_1_1;
        static String mExp2FogVs_1_1;

    public:
        /// General purpose method to get any of the program sources
        static const String& getProgramSource(FogMode fogMode, const String syntax);


    };
}

#endif
