Allow defining center of rotation for geometry.

MyWorldLLC · Apr 1, 2024 · c258895 · c258895
1 parent e41652d
commit c258895
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Showing 2 changed files with 12 additions and 3 deletions.
diff --git a/Obsidian/src/main/java/myworld/obsidian/display/Renderer.java b/Obsidian/src/main/java/myworld/obsidian/display/Renderer.java
@@ -132,6 +132,7 @@ public void render(Canvas canvas, Bounds2D componentBounds, String styleDebugNam
 
             Move position = style.rule(StyleRules.POSITION, renderVars);
             Rotate rotation = style.rule(StyleRules.ROTATION, renderVars);
+            Move rotationCenter = style.rule(StyleRules.ROTATION_CENTER, renderVars);
             Skew skew = style.rule(StyleRules.SKEW, renderVars);
 
             Matrix33 transform = Matrix33.IDENTITY;
@@ -151,9 +152,16 @@ public void render(Canvas canvas, Bounds2D componentBounds, String styleDebugNam
             }
 
             if (rotation != null) {
-                transform = Matrix33.makeRotate(-rotation.angle(),
-                                new Point(componentBounds.left() + componentBounds.width() / 2f,
-                                        componentBounds.top() + componentBounds.height() / 2f))
+                Point center;
+                if(rotationCenter != null){
+                    center = new Point(rotationCenter.x().toPixels(componentBounds.width()) - 0.5f,
+                            rotationCenter.y().toPixels(componentBounds.height()) - 0.5f);
+                }else{
+                    // If rotation center is not defined, use the drawing's center.
+                    center = new Point(componentBounds.left() + componentBounds.width() / 2f,
+                                    componentBounds.top() + componentBounds.height() / 2f);
+                }
+                transform = Matrix33.makeRotate(-rotation.angle(), center)
                         .makeConcat(transform);
             }
 

diff --git a/Obsidian/src/main/java/myworld/obsidian/display/skin/StyleRules.java b/Obsidian/src/main/java/myworld/obsidian/display/skin/StyleRules.java
@@ -8,6 +8,7 @@ public class StyleRules {
     public static final String COLOR = "color";
     public static final String POSITION = "position";
     public static final String ROTATION = "rotation";
+    public static final String ROTATION_CENTER = "rotation-center";
     public static final String SKEW = "skew";
 
     public static final String OVERFLOW_MODE = "overflow-mode";