avoid implicit conversion from vec4 to varying vec3

assets/fs/shaders/obj.v.glsl

@@ -12,5 +12,5 @@ void main(void)
 {
     gl_Position = projection * modelview * vec4(pos, 1);
     pos_i = gl_Position.xyz;
-    normal_i = modelview * vec4(normal, 0);
+    normal_i = (modelview * vec4(normal, 0)).xyz;
 }

assets/fs/shaders/obj_tex.v.glsl

@@ -15,5 +15,5 @@ void main(void)
     gl_Position = projection * modelview * vec4(pos, 1);
     pos_i = gl_Position.xyz;
     tex_coord_i = tex_coord;
-    normal_i = modelview * vec4(normal, 0);
+    normal_i = (modelview * vec4(normal, 0)).xyz;
 }