Implement texture atlas, details on why it works unclear

shader/texture/array.vert

@@ -0,0 +1,12 @@
+#version 430 core
+layout (location = 0) in vec3 pos;
+layout (location = 1) in vec3 texPos;
+out vec3 vTexPos;
+
+uniform mat4 worldMat;
+
+void main()
+{
+  gl_Position = worldMat * vec4(pos,1.0) ;
+  vTexPos = texPos;
+}