Terrain Tutorial

Smoothing - API Details

Three functions are provided in terrain.cpp (see the source code) for this effect. The first one resets the filter to the identity filter, i.e. a matrix full of zeroes with a single 1.0 value at the center. Applying this matrix is the same as lefting the terrain untouched.

void terrainResetFilter();

There is a function to set a filter. This function receives a 5x5 matrix as a 25 floats array.

void terrainSetFilter(float *newFilter);

Parameters:

newFilter - The array with the matrix coefficients

In the implementation provided the final height of a grid point after applying the matrix is divided by the sum of the matrix components. Therefore the following two matrices produce the same result:

    
	m = [ 1/9   1/9   1/9
	      1/9   1/9   1/9
	      1/9   1/9   1/9];
	      
	m = [ 1     1     1
	      1     1     1
	      1     1     1];

Note: The example above uses 3x3 matrices for simplification purposes. The function expects to receive an array with 25 floats, i.e. a 5x5 matrix.

Finally the function terrainApplyFilter will apply the matrix previously defined to all the terrain grid points.

int terrainApplyFilter();

The application provided in the source code includes a window where you can enter the matrix components and try your own filters. Please let me know if you get interesting results.

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