- template with an example of a modal operator drawing with opengl (draw a line on the screen)

- access to event.mouse_region_x/y
- basic type checking to callback functions (use PyCapsule names)

1 files changed, 69 insertions, 0 deletions

diff --git a/release/scripts/templates/operator_modal_draw.py b/release/scripts/templates/operator_modal_draw.py
new file mode 100644
index 00000000000..d830a380250
--- /dev/null
+++ b/release/scripts/templates/operator_modal_draw.py
@@ -0,0 +1,69 @@
+import BGL
+
+def draw_callback_px(self, context):
+    print("mouse points", len(self.mouse_path))    
+
+    # 50% alpha, 2 pixel width line
+    BGL.glEnable(BGL.GL_BLEND)
+    BGL.glColor4f(0.0, 0.0, 0.0, 0.5)
+    BGL.glLineWidth(2)
+
+    BGL.glBegin(BGL.GL_LINE_STRIP)
+    for x, y in self.mouse_path:
+        BGL.glVertex2i(x, y)
+
+    BGL.glEnd()
+
+    # restore opengl defaults 
+    BGL.glLineWidth(1)
+    BGL.glDisable(BGL.GL_BLEND)
+    BGL.glColor4f(0.0, 0.0, 0.0, 1.0)
+
+
+class ModalDrawOperator(bpy.types.Operator):
+    '''Draw a line with the mouse'''
+    bl_idname = "object.modal_operator"
+    bl_label = "Simple Modal Operator"
+
+    def modal(self, context, event):
+        context.area.tag_redraw()
+
+        if event.type == 'MOUSEMOVE':
+            self.mouse_path.append((event.mouse_region_x, event.mouse_region_y))
+
+        elif event.type == 'LEFTMOUSE':
+            context.region.callback_remove(self._handle)
+            return {'FINISHED'}
+
+        elif event.type in ('RIGHTMOUSE', 'ESC'):
+            context.region.callback_remove(self._handle)
+            return {'CANCELLED'}
+
+        return {'RUNNING_MODAL'}
+
+    def invoke(self, context, event):
+        if context.area.type == 'VIEW_3D':
+            context.manager.add_modal_handler(self)
+            
+            # Add the region OpenGL drawing callback
+            # draw in view space with 'POST_VIEW' and 'PRE_VIEW'
+            self._handle = context.region.callback_add(draw_callback_px, (self, context), 'POST_PIXEL')
+
+            self.mouse_path = []
+
+            return {'RUNNING_MODAL'}
+        else:
+            self.report({'WARNING'}, "View3D not found, cannot run operator")
+            return {'CANCELLED'}
+
+
+def register():
+    bpy.types.register(ModalDrawOperator)
+
+
+def unregister():
+    bpy.types.unregister(ModalDrawOperator)
+
+
+if __name__ == "__main__":
+    register()