src/shaders/updateHeightShader.comp

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#version 430

layout(local_size_x = 16, local_size_y = 16) in; 


//Since in previous step, (advectWater) we used this as inbuffer and height1 as out. Now we are interested in the new data and want to save it to a out buffer. height0 cotains nothing of value anymore. use it as out data. DO NOT SWAP IN CPP.

layout  (std430,binding = 4) writeonly buffer height0
{
    float water0[];
    
};

layout (std430, binding = 5) readonly buffer height1
{
    float water1[]; 
};


layout (std430,binding = 7) readonly buffer velocityXout
{
    float vxout[];
    
};


layout (std430,binding = 9) readonly buffer velocityYout
{   
    float vyout[];
    
};

layout (std430,binding = 10) readonly buffer Terrain 
{   
    float terr[];
    
};


uniform ivec2 size; 
uniform float dt; 

void main(){
    //determine where to sample
    ivec2 storePos = ivec2(gl_GlobalInvocationID.xy);
    int i = storePos.x;
    int j = storePos.y;
    int offset = (i + j*size.x);

    //Change these to clamps.
    if(i < size.x && j < size.y) {
        int ipos = clamp(i+1,0,size.x-1);
        int jpos = clamp(j+1,0,size.y-1);
        int imin = clamp(i-1,0,size.x-1);
        int jmin = clamp(j-1,0,size.y-1);
        
        int offsetXPlus = ipos+j*size.x;
        int offsetXMinus = imin+j*size.x;
        int offsetYMinus = i+jmin*size.x;
        int offsetYPlus = i+jpos*size.x;
        
        int xOrigin = i - int((vxout[offsetXPlus]- vxout[offset])*dt);
        int yOrigin = j - int((vyout[offsetYPlus] - vyout[offset])*dt);
        
        float deltaHeight = -0.5f*water1[offset]*((vxout[offsetXPlus]- vxout[offset])+(vyout[offsetYPlus] - vyout[offset]));
        /* For terrain some sort of clamp for water availability should be used.
        deltaHeight = clamp(deltaHeight, -water1[offset]*1000.0f,water1[xOrigin+yOrigin*size.x]);
        */
        
        
        water0[offset] = water1[offset]+deltaHeight*dt;
            
    }
}