/*********************************************************************NVMH3****
Copyright NVIDIA Corporation 2003
TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, THIS SOFTWARE IS PROVIDED
*AS IS* AND NVIDIA AND ITS SUPPLIERS DISCLAIM ALL WARRANTIES, EITHER EXPRESS
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL NVIDIA OR ITS SUPPLIERS
BE LIABLE FOR ANY SPECIAL, INCIDENTAL, INDIRECT, OR CONSEQUENTIAL DAMAGES
WHATSOEVER (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS OF BUSINESS PROFITS,
BUSINESS INTERRUPTION, LOSS OF BUSINESS INFORMATION, OR ANY OTHER PECUNIARY LOSS)
ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF NVIDIA HAS
BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.


Comments:
	Simple ocean shader with animated bump map and geometric waves
	Based partly on "Effective Water Simulation From Physical Models", GPU Gems
	
11 Aug 05: heavily modified by Jeff Doyle (nfz) for Ogre

******************************************************************************/



struct v2f {
	float4 Position  : POSITION;  // in clip space
	float3 rotMatrix1 : TEXCOORD0; // first row of the 3x3 transform from tangent to obj space
	float3 rotMatrix2 : TEXCOORD1; // second row of the 3x3 transform from tangent to obj space
	float3 rotMatrix3 : TEXCOORD2; // third row of the 3x3 transform from tangent to obj space

	float2 bumpCoord0 : TEXCOORD3;
	float2 bumpCoord1 : TEXCOORD4;
	float2 bumpCoord2 : TEXCOORD5;
	
	float3 eyeVector  : TEXCOORD6;
};


float4 main(v2f IN,
			uniform sampler2D NormalMap,
			uniform samplerCUBE EnvironmentMap,
			uniform float4 deepColor,
			uniform float4 shallowColor,
			uniform float4 reflectionColor,
			uniform float reflectionAmount,
			uniform float waterAmount,
			uniform float fresnelPower,
			uniform float fresnelBias,
			uniform float hdrMultiplier
			) : COLOR
{
	// sum normal maps
	// sample from 3 different points so no texture repetition is noticeable
    float4 t0 = tex2D(NormalMap, IN.bumpCoord0) * 2.0 - 1.0;
    float4 t1 = tex2D(NormalMap, IN.bumpCoord1) * 2.0 - 1.0;
    float4 t2 = tex2D(NormalMap, IN.bumpCoord2) * 2.0 - 1.0;
    float3 N = t0.xyz + t1.xyz + t2.xyz;

    float3x3 m; // tangent to world matrix
    m[0] = IN.rotMatrix1;
    m[1] = IN.rotMatrix2;
    m[2] = IN.rotMatrix3;
    
    N = normalize( mul( N, m ) );

	// reflection
    float3 E = normalize(IN.eyeVector);
    float3 R = reflect(E, N);
    // Ogre conversion for cube map lookup
    R.z = -R.z;

    float4 reflection = texCUBE(EnvironmentMap, R);
    // cheap hdr effect
    reflection.rgb *= (reflection.r + reflection.g + reflection.b) * hdrMultiplier;

	// fresnel 
    float facing = 1.0 - max(dot(-E, N), 0);
    float fresnel = saturate(fresnelBias + pow(facing, fresnelPower));

    float4 waterColor = lerp(shallowColor, deepColor, facing) * waterAmount;
    
    reflection = lerp(waterColor,  reflection * reflectionColor, fresnel) * reflectionAmount;
    return waterColor + reflection;
}