Remove a useless variable in the vertex shader

src/main.rs

@@ -42,15 +42,13 @@ fn main() {
                 in vec3 normal;
                 in vec2 tex_coords;
 
-                out vec3 v_position;
                 out vec3 v_normal;
                 out vec2 v_tex_coords;
 
                 void main() {
-                    v_position = position;
                     v_normal = normal;
                     v_tex_coords = tex_coords;
-                    gl_Position = persp_matrix * view_matrix * vec4(v_position * 0.005, 1.0);
+                    gl_Position = persp_matrix * view_matrix * vec4(position * 0.005, 1.0);
                 }
             ",