UI: Remove unnecessary vertices for preview

This change reduces the number of triangles drawn using a TRISTRIP while
still producing the same shapes for parts of the preview.

UI/window-basic-main.cpp

@@ -1452,9 +1452,8 @@ void OBSBasic::InitPrimitives()
 	gs_render_start(true);
 	gs_vertex2f(0.0f, 0.0f);
 	gs_vertex2f(0.0f, 1.0f);
-	gs_vertex2f(1.0f, 1.0f);
 	gs_vertex2f(1.0f, 0.0f);
-	gs_vertex2f(0.0f, 0.0f);
+	gs_vertex2f(1.0f, 1.0f);
 	box = gs_render_save();
 
 	gs_render_start(true);

UI/window-basic-preview.cpp

@@ -1514,10 +1514,9 @@ static void DrawLine(float x1, float y1, float x2, float y2, float thickness,
 	gs_vertex2f(x1, y1);
 	gs_vertex2f(x1 + (xSide * (thickness / scale.x)),
 		    y1 + (ySide * (thickness / scale.y)));
+	gs_vertex2f(x2, y2);
 	gs_vertex2f(x2 + (xSide * (thickness / scale.x)),
 		    y2 + (ySide * (thickness / scale.y)));
-	gs_vertex2f(x2, y2);
-	gs_vertex2f(x1, y1);
 
 	gs_vertbuffer_t *line = gs_render_save();
 
@@ -1532,24 +1531,17 @@ static void DrawRect(float thickness, vec2 scale)
 
 	gs_vertex2f(0.0f, 0.0f);
 	gs_vertex2f(0.0f + (thickness / scale.x), 0.0f);
-	gs_vertex2f(0.0f + (thickness / scale.x), 1.0f);
-	gs_vertex2f(0.0f, 1.0f);
-	gs_vertex2f(0.0f, 0.0f);
 	gs_vertex2f(0.0f, 1.0f);
+	gs_vertex2f(0.0f + (thickness / scale.x), 1.0f);
 	gs_vertex2f(0.0f, 1.0f - (thickness / scale.y));
-	gs_vertex2f(1.0f, 1.0f - (thickness / scale.y));
-	gs_vertex2f(1.0f, 1.0f);
-	gs_vertex2f(0.0f, 1.0f);
 	gs_vertex2f(1.0f, 1.0f);
+	gs_vertex2f(1.0f, 1.0f - (thickness / scale.y));
 	gs_vertex2f(1.0f - (thickness / scale.x), 1.0f);
-	gs_vertex2f(1.0f - (thickness / scale.x), 0.0f);
-	gs_vertex2f(1.0f, 0.0f);
-	gs_vertex2f(1.0f, 1.0f);
 	gs_vertex2f(1.0f, 0.0f);
+	gs_vertex2f(1.0f - (thickness / scale.x), 0.0f);
 	gs_vertex2f(1.0f, 0.0f + (thickness / scale.y));
-	gs_vertex2f(0.0f, 0.0f + (thickness / scale.y));
 	gs_vertex2f(0.0f, 0.0f);
-	gs_vertex2f(1.0f, 0.0f);
+	gs_vertex2f(0.0f, 0.0f + (thickness / scale.y));
 
 	gs_vertbuffer_t *rect = gs_render_save();
 
@@ -1897,10 +1889,8 @@ void OBSBasicPreview::DrawSceneEditing()
 
 			gs_vertex2f(0.0f, 0.0f);
 			gs_vertex2f(1.0f, 0.0f);
-			gs_vertex2f(1.0f, 1.0f);
-			gs_vertex2f(1.0f, 1.0f);
-			gs_vertex2f(0.0f, 0.0f);
 			gs_vertex2f(0.0f, 1.0f);
+			gs_vertex2f(1.0f, 1.0f);
 
 			rectFill = gs_render_save();
 		}