I implemented "The Sum of Sines Approximation" in this article: https://developer.nvidia.com/gpugems/gpugems/part-i-natural-effects/chapter-1-effective-water-simulation-physical-models
My geometry is working fine, but the normals are somewhat wrong. They x- and z-values are flipped, and I wonder what i did wrong in the implementation.
The following equations are used:
The generation of the normals looks like this in the shader:
vec3 generateWaveSineSumNormal(sineParams _params[sineCount])
{
vec2 pos = vec2(aPos.x, aPos.z);
vec3 normal = vec3(0.0f, 1.0f, 0.0f);
for(int i=0; i<sineCount; i++)
{
sinParams curParams = _params[i];
normal.x += sineExponent * curParams.direction.x * curParams.frequency * curParams.amplitude *
pow((sin(dot(curParams.direction, pos) * curParams.frequency + curTime * curParams.speed)+1)/2, sineExponent-1)
* cos(dot(curParams.direction, pos) * curParams.frequency + curTime * curParams.speed);
normal.z += sineExponent * curParams.direction.y * curParams.frequency * curParams.amplitude *
pow((sin(dot(curParams.direction, pos) * curParams.frequency + curTime * curParams.speed)+1)/2, sineExponent-1)
* cos(dot(curParams.direction, pos) * curParams.frequency + curTime * curParams.speed);
}
return vec3(-normal.x, normal.y, -normal.z);
}
When the x- and z-values are flipped like this, the normals are fine. I'm just wondering what I did wrong implementing it, since I just can't find it.
