Merge pull request #327 from roudy16/fix/normal-map-cardinality

enable right-handed normal maps

code/intermediate/tutorial11-normals/src/model.rs

@@ -219,7 +219,9 @@ impl Model {
                 // the solution!
                 let r = 1.0 / (delta_uv1.x * delta_uv2.y - delta_uv1.y * delta_uv2.x);
                 let tangent = (delta_pos1 * delta_uv2.y - delta_pos2 * delta_uv1.y) * r;
-                let bitangent = (delta_pos2 * delta_uv1.x - delta_pos1 * delta_uv2.x) * r;
+                // We flip the bitangent to enable right-handed normal
+                // maps with wgpu texture coordinate system
+                let bitangent = (delta_pos2 * delta_uv1.x - delta_pos1 * delta_uv2.x) * -r;
 
                 // We'll use the same tangent/bitangent for each vertex in the triangle
                 vertices[c[0] as usize].tangent =

code/intermediate/tutorial12-camera/src/model.rs

@@ -219,7 +219,9 @@ impl Model {
                 // the solution!
                 let r = 1.0 / (delta_uv1.x * delta_uv2.y - delta_uv1.y * delta_uv2.x);
                 let tangent = (delta_pos1 * delta_uv2.y - delta_pos2 * delta_uv1.y) * r;
-                let bitangent = (delta_pos2 * delta_uv1.x - delta_pos1 * delta_uv2.x) * r;
+                // We flip the bitangent to enable right-handed normal
+                // maps with wgpu texture coordinate system
+                let bitangent = (delta_pos2 * delta_uv1.x - delta_pos1 * delta_uv2.x) * -r;
 
                 // We'll use the same tangent/bitangent for each vertex in the triangle
                 vertices[c[0] as usize].tangent =

code/intermediate/tutorial13-threading/src/model.rs

@@ -219,7 +219,9 @@ impl Model {
                 // the solution!
                 let r = 1.0 / (delta_uv1.x * delta_uv2.y - delta_uv1.y * delta_uv2.x);
                 let tangent = (delta_pos1 * delta_uv2.y - delta_pos2 * delta_uv1.y) * r;
-                let bitangent = (delta_pos2 * delta_uv1.x - delta_pos1 * delta_uv2.x) * r;
+                // We flip the bitangent to enable right-handed normal
+                // maps with wgpu texture coordinate system
+                let bitangent = (delta_pos2 * delta_uv1.x - delta_pos1 * delta_uv2.x) * -r;
 
                 // We'll use the same tangent/bitangent for each vertex in the triangle
                 vertices[c[0] as usize].tangent =

docs/intermediate/tutorial11-normals/README.md

@@ -278,7 +278,9 @@ impl Model {
                 // the solution!
                 let r = 1.0 / (delta_uv1.x * delta_uv2.y - delta_uv1.y * delta_uv2.x);
                 let tangent = (delta_pos1 * delta_uv2.y - delta_pos2 * delta_uv1.y) * r;
-                let bitangent = (delta_pos2 * delta_uv1.x - delta_pos1 * delta_uv2.x) * r;
+                // We flip the bitangent to enable right-handed normal
+                // maps with wgpu texture coordinate system
+                let bitangent = (delta_pos2 * delta_uv1.x - delta_pos1 * delta_uv2.x) * -r;
 
                 // We'll use the same tangent/bitangent for each vertex in the triangle
                 vertices[c[0] as usize].tangent =