feat: refine scene viewport gizmos and controls

editor/src/Viewport/SceneViewportMath.h

@@ -107,6 +107,70 @@ inline bool ProjectSceneViewportAxisDirection(
     return true;
 }
 
+inline bool ProjectSceneViewportAxisDirectionAtPoint(
+    const SceneViewportOverlayData& overlay,
+    float viewportWidth,
+    float viewportHeight,
+    const Math::Vector3& worldPoint,
+    const Math::Vector3& worldAxis,
+    Math::Vector2& outScreenDirection,
+    float sampleDistance = 1.0f) {
+    const Math::Vector3 axis = worldAxis.Normalized();
+    if (!overlay.valid ||
+        viewportWidth <= 1.0f ||
+        viewportHeight <= 1.0f ||
+        axis.SqrMagnitude() <= Math::EPSILON ||
+        sampleDistance <= Math::EPSILON) {
+        return false;
+    }
+
+    const Math::Matrix4x4 viewProjection =
+        BuildSceneViewportViewProjectionMatrix(overlay, viewportWidth, viewportHeight);
+    const Math::Vector4 startClip = viewProjection * Math::Vector4(worldPoint, 1.0f);
+    const Math::Vector4 endClip = viewProjection * Math::Vector4(worldPoint + axis * sampleDistance, 1.0f);
+    if (startClip.w <= Math::EPSILON || endClip.w <= Math::EPSILON) {
+        return ProjectSceneViewportAxisDirection(overlay, axis, outScreenDirection);
+    }
+
+    const Math::Vector3 startNdc = startClip.ToVector3() / startClip.w;
+    const Math::Vector3 endNdc = endClip.ToVector3() / endClip.w;
+    const Math::Vector2 startScreen(
+        (startNdc.x * 0.5f + 0.5f) * viewportWidth,
+        (1.0f - (startNdc.y * 0.5f + 0.5f)) * viewportHeight);
+    const Math::Vector2 endScreen(
+        (endNdc.x * 0.5f + 0.5f) * viewportWidth,
+        (1.0f - (endNdc.y * 0.5f + 0.5f)) * viewportHeight);
+
+    const Math::Vector2 screenDirection = endScreen - startScreen;
+    if (screenDirection.SqrMagnitude() <= Math::EPSILON) {
+        return ProjectSceneViewportAxisDirection(overlay, axis, outScreenDirection);
+    }
+
+    outScreenDirection = screenDirection.Normalized();
+    return true;
+}
+
+inline bool ProjectSceneViewportWorldPointClamped(
+    const SceneViewportOverlayData& overlay,
+    float viewportWidth,
+    float viewportHeight,
+    const Math::Vector3& worldPoint,
+    float edgePadding,
+    SceneViewportProjectedPoint& outProjectedPoint) {
+    outProjectedPoint = ProjectSceneViewportWorldPoint(overlay, viewportWidth, viewportHeight, worldPoint);
+    if (!overlay.valid || viewportWidth <= 1.0f || viewportHeight <= 1.0f || outProjectedPoint.ndcDepth < 0.0f) {
+        return false;
+    }
+
+    const float minX = edgePadding;
+    const float minY = edgePadding;
+    const float maxX = viewportWidth - edgePadding;
+    const float maxY = viewportHeight - edgePadding;
+    outProjectedPoint.screenPosition.x = std::clamp(outProjectedPoint.screenPosition.x, minX, maxX);
+    outProjectedPoint.screenPosition.y = std::clamp(outProjectedPoint.screenPosition.y, minY, maxY);
+    return true;
+}
+
 inline float DistanceToSegmentSquared(
     const Math::Vector2& point,
     const Math::Vector2& segmentStart,