Merge pull request glium#1940 from marcianx/master

Correct formulas in the normal mapping tutorial.

book/tuto-14-wall.md

@@ -187,7 +187,7 @@ Thanks to this we can calculate the *real* normal, in other words the normal of
 at the given pixel:
 
 ```glsl
-mat3 tbn = cotangent_frame(v_normal, v_position, v_tex_coords);
+mat3 tbn = cotangent_frame(v_normal, -v_position, v_tex_coords);
 vec3 real_normal = normalize(tbn * -(normal_map * 2.0 - 1.0));
 ```
 

examples/tutorial-14.rs

@@ -100,8 +100,9 @@ fn main() {
  vec3 diffuse_color = texture(diffuse_tex, v_tex_coords).rgb;
  vec3 ambient_color = diffuse_color * 0.1;
 
+ vec3 v_normal_unit = normalize(v_normal);
  vec3 normal_map = texture(normal_tex, v_tex_coords).rgb;
- mat3 tbn = cotangent_frame(v_normal, v_position, v_tex_coords);
+ mat3 tbn = cotangent_frame(v_normal_unit, -v_position, v_tex_coords);
  vec3 real_normal = normalize(tbn * -(normal_map * 2.0 - 1.0));
 
  float diffuse = max(dot(real_normal, normalize(u_light)), 0.0);
@@ -117,6 +118,7 @@ fn main() {
  let program = glium::Program::from_source(&display, vertex_shader_src, fragment_shader_src,
  None).unwrap();
 
+ let start = std::time::Instant::now();
  event_loop.run(move |event, _, control_flow| {
  let next_frame_time = std::time::Instant::now() +
  std::time::Duration::from_nanos(16_666_667);
@@ -141,10 +143,13 @@ fn main() {
  let mut target = display.draw();
  target.clear_color_and_depth((0.0, 0.0, 1.0, 1.0), 1.0);
 
+ let t = (std::time::Instant::now() - start).as_secs_f32() * 2.0;
+ let ang = t.sin();
+ let (c, s) = (ang.cos(), ang.sin());
  let model = [
- [1.0, 0.0, 0.0, 0.0],
+ [ c, 0.0,  s, 0.0],
  [0.0, 1.0, 0.0, 0.0],
- [0.0, 0.0, 1.0, 0.0],
+ [ -s, 0.0,  c, 0.0],
  [0.0, 0.0, 0.0, 1.0f32]
  ];