2808: fix incorrect UV grid picking when texture is rotated/sheared (T…

…renchBroom#2860) Fixes TrenchBroom#2808
Switch-9867 · Dec 8, 2019 · b5aa802 · b5aa802
1 parent a48ae14
commit b5aa802
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Showing 2 changed files with 28 additions and 11 deletions.
diff --git a/common/src/View/UVViewHelper.cpp b/common/src/View/UVViewHelper.cpp
@@ -131,23 +131,29 @@ namespace TrenchBroom {
                 const auto& boundary = m_face->boundary();
                 const FloatType distance = vm::intersect_ray_plane(ray, boundary);
                 const vm::vec3  hitPointInWorldCoords = vm::point_at_distance(ray, distance);
-                const vm::vec3  hitPointInTexCoords = m_face->toTexCoordSystemMatrix(m_face->offset(), m_face->scale(), true) * hitPointInWorldCoords;
-                const vm::vec2f hitPointInViewCoords = m_camera.project(vm::vec3f(hitPointInWorldCoords)).xy();
+                const vm::vec2f hitPointInTexCoords = vm::vec2f(m_face->toTexCoordSystemMatrix(m_face->offset(), m_face->scale(), true) * hitPointInWorldCoords);
+                const vm::vec2f hitPointInViewCoords = texToViewCoords(hitPointInTexCoords);
 
-                const vm::vec2f closestGridInTexCoords = vm::vec2f(hitPointInTexCoords) + computeDistanceFromTextureGrid(hitPointInTexCoords);
-                const vm::vec3  closestGridInWorldCoords = m_face->fromTexCoordSystemMatrix(m_face->offset(), m_face->scale(), true) * vm::vec3(closestGridInTexCoords, 0.0f);
-                const vm::vec2f closestGridInViewCoords = m_camera.project(vm::vec3f(closestGridInWorldCoords)).xy();
-
-                // X and Y distance in pixels to the closest grid intersection
-                // (i.e. so the X component is the distance from the closest vertical gridline, and the
+                // X and Y distance in texels to the closest grid intersection.
+                // (i.e. so the X component is the distance to the closest vertical gridline, and the
                 // Y the distance to the closest horizontal gridline.)
+                const vm::vec2f distanceFromGridTexCoords = computeDistanceFromTextureGrid(vm::vec3(hitPointInTexCoords, 0.0f));
+                const vm::vec2f closestPointsOnGridInTexCoords[2] = {
+                    hitPointInTexCoords + vm::vec2f(distanceFromGridTexCoords.x(), 0.0f), // closest point on a vertical gridline
+                    hitPointInTexCoords + vm::vec2f(0.0f, distanceFromGridTexCoords.y()), // closest point on a horizontal gridline
+                };
+
                 // FIXME: should be measured in points so the grid isn't harder to hit with high-DPI
-                const vm::vec2f distToClosestGridInScreenCoords = vm::abs(closestGridInViewCoords - hitPointInViewCoords);
-                // FIXME: factor out and share with other tools, possibly as preference
+                const float distToClosestGridInViewCoords[2] = {
+                    vm::distance(hitPointInViewCoords, texToViewCoords(closestPointsOnGridInTexCoords[0])),
+                    vm::distance(hitPointInViewCoords, texToViewCoords(closestPointsOnGridInTexCoords[1]))
+                };
+
+                // FIXME: factor out and share with other tools
                 constexpr float maxDistance = static_cast<float>(5.0);
 
                 for (size_t i = 0; i < 2; ++i) {
-                    const float error = distToClosestGridInScreenCoords[i];
+                    const float error = distToClosestGridInViewCoords[i];
 
                     if (error <= maxDistance) {
                         const vm::vec2 stripeSize = UVViewHelper::stripeSize();
@@ -207,6 +213,12 @@ namespace TrenchBroom {
             y2 = toWorld * vm::vec3(max.x(), pos.y(), 0.0);
         }
 
+        vm::vec2f UVViewHelper::texToViewCoords(const vm::vec2f& pos) const {
+            const vm::vec3  posInWorldCoords = m_face->fromTexCoordSystemMatrix(m_face->offset(), m_face->scale(), true) * vm::vec3(pos, 0.0f);
+            const vm::vec2f posInViewCoords = m_camera.project(vm::vec3f(posInWorldCoords)).xy();
+            return posInViewCoords;
+        }
+
         void UVViewHelper::resetOrigin() {
             assert(valid());
 

diff --git a/common/src/View/UVViewHelper.h b/common/src/View/UVViewHelper.h
@@ -85,6 +85,11 @@ namespace TrenchBroom {
             void computeOriginHandleVertices(vm::vec3& x1, vm::vec3& x2, vm::vec3& y1, vm::vec3& y2) const;
             void computeScaleHandleVertices(const vm::vec2& pos, vm::vec3& x1, vm::vec3& x2, vm::vec3& y1, vm::vec3& y2) const;
             void computeLineVertices(const vm::vec2& pos, vm::vec3& x1, vm::vec3& x2, vm::vec3& y1, vm::vec3& y2, const vm::mat4x4& toTex, const vm::mat4x4& toWorld) const;
+
+            /**
+             * Converts texture space to view space (pixels in the UV viewport).
+             */
+            vm::vec2f texToViewCoords(const vm::vec2f& pos) const;
         private:
             void resetOrigin();
             void resetCamera();