Added selection rectangle.

src/ui/rectangle.h

@@ -0,0 +1,21 @@
+/**
+ * Copyright (c) 2021 Dominic Masters
+ * 
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include <dawn/dawn.h>
+#include "../display/texture.h"
+#include "../display/shader.h"
+#include "../display/primitive.h"
+#include "../display/primitives/quad.h"
+
+void rectangleInit(rectangle_t *rectangle);
+
+void rectangleSetColor(rectangle_t *rectangle, pixel_t color);
+
+void rectangleRender(rectangle_t *rectangle, shader_t *shader);
+
+void rectangleDispose(rectangle_t *rectangle);