Function R_AddNormalMaps

neo/renderer/Image_program.cpp:195–242

=================== R_AddNormalMaps =================== */

===================
*/
static void R_AddNormalMaps( byte *data1, int width1, int height1, byte *data2, int width2, int height2 ) {
	int		i, j;
	byte	*newMap;

	// resample pic2 to the same size as pic1
	if ( width2 != width1 || height2 != height1 ) {
		newMap = R_Dropsample( data2, width2, height2, width1, height1 );
		data2 = newMap;
	} else {
		newMap = NULL;
	}

	// add the normal change from the second and renormalize
	for ( i = 0 ; i < height1 ; i++ ) {
		for ( j = 0 ; j < width1 ; j++ ) {
			byte	*d1, *d2;
			idVec3	n;
			float   len;

			d1 = data1 + ( i * width1 + j ) * 4;
			d2 = data2 + ( i * width1 + j ) * 4;

			n[0] = ( d1[0] - 128 ) / 127.0;
			n[1] = ( d1[1] - 128 ) / 127.0;
			n[2] = ( d1[2] - 128 ) / 127.0;

			// There are some normal maps that blend to 0,0,0 at the edges
			// this screws up compression, so we try to correct that here by instead fading it to 0,0,1
			len = n.LengthFast();
			if ( len < 1.0f ) {
				n[2] = idMath::Sqrt(1.0 - (n[0]*n[0]) - (n[1]*n[1]));
			}

			n[0] += ( d2[0] - 128 ) / 127.0;
			n[1] += ( d2[1] - 128 ) / 127.0;
			n.Normalize();

			d1[0] = (byte)(n[0] * 127 + 128);
			d1[1] = (byte)(n[1] * 127 + 128);
			d1[2] = (byte)(n[2] * 127 + 128);
			d1[3] = 255;
		}
	}

	if ( newMap ) {
		R_StaticFree( newMap );
	}
}

/*
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