VT redraw on request

Former-commit-id: 3ada71215d9291760704a982cc3952061dbc7afe
Former-commit-id: ca1495e668e88bc7214429472ad918621a650189

assets/test.vert

@@ -0,0 +1,14 @@
+attribute vec4 a_position;
+attribute vec4 a_color;
+attribute vec2 a_texCoord0;
+
+uniform mat4 u_projTrans;
+
+varying vec4 v_color;
+varying vec2 v_texCoords;
+
+void main() {
+    v_color = a_color;
+    v_texCoords = a_texCoord0;
+    gl_Position = u_projTrans * a_position;
+}