diff --git a/c++/perspective/src/mainwindow.cpp b/c++/perspective/src/mainwindow.cpp
index 6537032..fce4a8b 100644
--- a/c++/perspective/src/mainwindow.cpp
+++ b/c++/perspective/src/mainwindow.cpp
@@ -121,7 +121,12 @@ MainWindow::update_dst_surface() {
 	std::cout << "update_dst_surface() - begin" << std::endl;
 
 	dst_surface.clear();
-
+	
+	// full dst_bounds
+	const IntPair2 full_dst_bounds_pixels(
+		IntVector2(0, 0),
+		IntVector2(src_view.get_width(), src_view.get_height()) );
+	
 	// src matrix
 	const Pair2 src_bounds(
 		src_rect_p0->position,
@@ -182,8 +187,12 @@ MainWindow::update_dst_surface() {
 	Perspective::print_layers(layers, Log::tab(2));
 	std::cout << Log::tab() << "---------------" << std::endl;
 	
+	// override dst_bounds
+	for(Perspective::LayerList::iterator i = layers.begin(); i != layers.end(); ++i)
+		i->dst_bounds = full_dst_bounds_pixels;
+	
 	// make surface
-	DataSurface surface(dst_bounds_pixels.p1.x, dst_bounds_pixels.p1.y);
+	DataSurface surface(full_dst_bounds_pixels.p1.x, full_dst_bounds_pixels.p1.y);
 	for(Perspective::LayerList::const_iterator i = layers.begin(); i != layers.end(); ++i) {
 		DataSurface layer_surface(i->src_size.x, i->src_size.y);
 		generator.generate(layer_surface, i->src_bounds);
diff --git a/c++/perspective/src/perspective.cpp b/c++/perspective/src/perspective.cpp
index 51a9438..fff728f 100644
--- a/c++/perspective/src/perspective.cpp
+++ b/c++/perspective/src/perspective.cpp
@@ -178,10 +178,6 @@ Perspective::make_alpha_matrix(
 	Real bw0, Real bw1,
 	const Vector3 &w_col )
 {
-	return Matrix3(
-		Vector3( 0, 0, 0 ),
-		Vector3( 0, 0, 0 ),
-		Vector3( 1, 1, 1 ) );
 	const Vector3 a_col = make_alpha_matrix_col(aw0, aw1, w_col);
 	const Vector3 b_col = make_alpha_matrix_col(bw0, bw1, w_col);
 	return Matrix3(
@@ -359,13 +355,13 @@ Perspective::create_layers(
 			}
 		}
 		Vector2 line[2];
-		int line_count = truncate_line(line, Pair2(dst_bounds), A, B, 1/w0 - C);
+		int line_count = truncate_line(line, Pair2(dst_bounds), A, B, C - 1/w0);
 		for(int j = 0; j < line_count; ++j) {
 			layer_src_bounds.expand( (back_matrix * Vector3(line[j], 1)).vec2() * w0 );
 			layer_dst_bounds.expand( line[j] );
 		}
 		
-		line_count = truncate_line(line, Pair2(dst_bounds), A, B, 1/w1 - C);
+		line_count = truncate_line(line, Pair2(dst_bounds), A, B, C - 1/w1);
 		for(int j = 0; j < line_count; ++j) {
 			layer_src_bounds.expand( (back_matrix * Vector3(line[j], 1)).vec2() * w1 );
 			layer_dst_bounds.expand( line[j] );
@@ -390,7 +386,7 @@ Perspective::create_layers(
 			Vector2(layer.dst_bounds.size()) );
 		layer.back_matrix *= back_matrix;
 		layer.back_alpha_matrix = make_alpha_matrix(
-			aw0, aw1, bw0, bw1,
+			1/aw0, 1/aw1, 1/bw0, 1/bw1,
 			layer.back_matrix.get_col(2) );
 		out_layers.push_back(layer);
 	}