medfall

commit 160046f721c555f5d5af793d9ce0c5ca71181383
parent ab6c98400312486a653c2700da10c2a0437cd4da
Author: Michael Savage <mikejsavage@gmail.com>
Date:   Sun Nov 13 22:21:15 +0200

Warnings, helpful comment

Diffstat:
pp.cc
 | 
12
++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/pp.cc b/pp.cc
@@ -62,6 +62,8 @@ static void compute_horizons(
 }
 
 static void compute_normals( const array2d< u8 > heightmap, array2d< v3 > normals ) {
+	// estimate the gradient at each point by doing central differences on
+	// each axis, then cross the tangent and bitangent to find the normal
 	for( size_t y = 0; y < heightmap.h; y++ ) {
 		for( size_t x = 0; x < heightmap.w; x++ ) {
 			size_t x_plus_one = x + 1;
@@ -74,8 +76,14 @@ static void compute_normals( const array2d< u8 > heightmap, array2d< v3 > normal
 			if( y == 0 ) y_minus_one = y;
 			if( y == heightmap.h - 1 ) y_plus_one = y;
 
-			v3 tangent( checked_cast< float >( x_plus_one - x_minus_one ), 0.0f, heightmap( x_plus_one, y ) - heightmap( x_minus_one, y ) );
-			v3 bitangent( 0.0f, checked_cast< float >( y_plus_one - y_minus_one ), heightmap( x, y_plus_one ) - heightmap( x, y_minus_one ) );
+			v3 tangent(
+				checked_cast< float >( x_plus_one - x_minus_one ),
+				0.0f,
+				checked_cast< float >( heightmap( x_plus_one, y ) - heightmap( x_minus_one, y ) ) );
+			v3 bitangent(
+				0.0f,
+				checked_cast< float >( y_plus_one - y_minus_one ),
+				checked_cast< float >( heightmap( x, y_plus_one ) - heightmap( x, y_minus_one ) ) );
 
 			normals( x, y ) = normalize( cross( tangent, bitangent ) );
 		}