Now have multiple lights.

13-multiple-lights/shaders/3.3.shader.vs

@@ -0,0 +1,11 @@
+#version 330 core
+layout (location = 0) in vec3 aPos; // the position variable has attribute position 0
+layout (location = 1) in vec3 aColor;
+
+out vec3 ourColor;
+
+void main()
+{
+    gl_Position = vec4(aPos, 1.0); // see how we directly give a vec3 to vec4's constructor
+    ourColor = aColor;
+}