source: data/branches/Shader_HS18/programs/GLSL120/Ocean2GLSL.frag @ 12115

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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: converted from HLSL to GLSL by Jeff Doyle (nfz) to work in Ogre

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


uniform sampler2D NormalMap;
uniform samplerCube EnvironmentMap;
uniform vec4 deepColor;
uniform vec4 shallowColor;
uniform vec4 reflectionColor;
uniform float reflectionAmount;
uniform float reflectionBlur;
uniform float waterAmount;
uniform float fresnelPower;
uniform float fresnelBias;
uniform float hdrMultiplier;

varying mat3 rotMatrix; // first row of the 3x3 transform from tangent to cube space
varying vec2 bumpCoord0;
varying vec2 bumpCoord1;
varying vec2 bumpCoord2;
varying vec3 eyeVector;


void main(void)
{
        // sum normal maps
        // sample from 3 different points so no texture repetition is noticeable
    vec4 t0 = texture2D(NormalMap, bumpCoord0) * 2.0 - 1.0;
    vec4 t1 = texture2D(NormalMap, bumpCoord1) * 2.0 - 1.0;
    vec4 t2 = texture2D(NormalMap, bumpCoord2) * 2.0 - 1.0;
    vec3 N = t0.xyz + t1.xyz + t2.xyz;

    N = normalize(rotMatrix * N);

        // reflection
    vec3 E = normalize(eyeVector);
    vec3 R = reflect(E, N);
    // Ogre conversion for cube map lookup
    R.z = -R.z;

    vec4 reflection = textureCube(EnvironmentMap, R, reflectionBlur);
    // cheap hdr effect
    reflection.rgb *= (reflection.r + reflection.g + reflection.b) * hdrMultiplier;

        // fresnel
    float facing = 1.0 - dot(-E, N);
    float fresnel = clamp(fresnelBias + pow(facing, fresnelPower), 0.0, 1.0);

    vec4 waterColor = mix(shallowColor, deepColor, facing) * waterAmount;

    reflection = mix(waterColor,  reflection * reflectionColor, fresnel) * reflectionAmount;
    gl_FragColor = waterColor + reflection;
}