Use geometry shader for widgets.

data/shaders/menu.frag

@@ -13,4 +13,5 @@ uniform Material u_material;
 void main()
 {
     f_color = texture(u_material.texture_diffuse0, v_texCoord);
+    // f_color = vec4(1.0, 0.0, 0.0, 0.5);
 }

data/shaders/menu.geom

@@ -0,0 +1,41 @@
+#version 330 core
+
+layout(points) in;
+layout(triangle_strip, max_vertices = 4) out;
+
+struct WidgetData
+{
+    vec2 position;
+    vec2 dimensions;
+};
+uniform WidgetData u_widgetData;
+
+out vec2 v_texCoord;
+
+void main()
+{
+    float glWidth = u_widgetData.dimensions.x * 2.0f;
+    float glHeight = u_widgetData.dimensions.y * 2.0f;
+
+    vec4 offset = vec4(0.0, 0.0, 0.0, 0.0);
+    gl_Position = gl_in[0].gl_Position + offset;
+    v_texCoord = vec2(0.0, 0.0);
+    EmitVertex();
+
+    offset = vec4(glWidth, 0.0, 0.0, 0.0);
+    gl_Position = gl_in[0].gl_Position + offset;
+    v_texCoord = vec2(1.0, 0.0);
+    EmitVertex();
+
+    offset = vec4(0.0, glHeight, 0.0, 0.0);
+    gl_Position = gl_in[0].gl_Position + offset;
+    v_texCoord = vec2(0.0, 1.0);
+    EmitVertex();
+
+    offset = vec4(glWidth, glHeight, 0.0, 0.0);
+    gl_Position = gl_in[0].gl_Position + offset;
+    v_texCoord = vec2(1.0, 1.0);
+    EmitVertex();
+
+    EndPrimitive();
+}

data/shaders/menu.vert

@@ -1,12 +1,16 @@
 #version 330 core
 
-layout(location = 0) in vec3 a_position;
-layout(location = 1) in vec2 a_texCoord;
-
-out vec2 v_texCoord;
+struct WidgetData
+{
+    vec2 position;
+    vec2 dimensions;
+};
+uniform WidgetData u_widgetData;
 
 void main()
 {
-    v_texCoord = a_texCoord;
-    gl_Position = vec4(a_position, 1.0);
+    float glPosX = u_widgetData.position.x * 2.0f - 1.0f;
+    float glPosY = u_widgetData.position.y * 2.0f - 1.0f;
+
+    gl_Position = vec4(glPosX, glPosY, 0, 1);
 }

data/shaders/postprocessing.vert

@@ -2,10 +2,11 @@
 
 out vec2 v_tex_coords;
 
-void main() {
+void main()
+{
     float x = -1.0 + float((gl_VertexID & 1) << 2);
     float y = -1.0 + float((gl_VertexID & 2) << 1);
-    v_tex_coords.x = (x+1.0)*0.5;
-    v_tex_coords.y = (y+1.0)*0.5;
+    v_tex_coords.x = (x + 1.0) * 0.5;
+    v_tex_coords.y = (y + 1.0) * 0.5;
     gl_Position = vec4(x, y, 0, 1);
 }