Add chapter 2.1-end

resources/backing.fs

@@ -0,0 +1,12 @@
+#version 330 core
+out vec4 FragColor;
+
+in vec2 TexCoords;
+
+uniform sampler2D screenTexture;
+
+void main()
+{
+    vec3 col = texture(screenTexture, TexCoords).rgb;
+    FragColor = vec4(col, 1.0);
+}