From a72cfc1d2e9382f14ca2e06b46323f1431c967dd Mon Sep 17 00:00:00 2001
From: Kjetil Orbekk <kjetil.orbekk@gmail.com>
Date: Wed, 6 Jul 2016 22:38:52 -0400
Subject: 1.6 Textures.

---
 rust/opengl/Cargo.toml  |  2 +-
 rust/opengl/src/main.rs | 49 ++++++++++++++++++++++++++++++++++---------------
 2 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/rust/opengl/Cargo.toml b/rust/opengl/Cargo.toml
index 6407830..8c14875 100644
--- a/rust/opengl/Cargo.toml
+++ b/rust/opengl/Cargo.toml
@@ -5,4 +5,4 @@ authors = ["Kjetil Orbekk <kjetil.orbekk@gmail.com>"]
 
 [dependencies]
 glium = "0.14.0"
-
+image = "*"
diff --git a/rust/opengl/src/main.rs b/rust/opengl/src/main.rs
index 29ee2ec..20834ca 100644
--- a/rust/opengl/src/main.rs
+++ b/rust/opengl/src/main.rs
@@ -1,9 +1,17 @@
 #[macro_use]
 extern crate glium;
+extern crate image;
+
+use std::io::Cursor;
+use glium::DisplayBuild;
+use glium::Surface;
 
 fn main() {
-    use glium::DisplayBuild;
-    use glium::Surface;
+    let image = image::load(Cursor::new(&include_bytes!("data/image.png")[..]),
+                            image::PNG).unwrap().to_rgba();
+    let image_dimensions = image.dimensions();
+    let image = glium::texture::RawImage2d::from_raw_rgba_reversed(
+        image.into_raw(), image_dimensions);
 
     let display = glium::glutin::WindowBuilder::new()
         .with_dimensions(1024, 768)
@@ -11,16 +19,19 @@ fn main() {
         .build_glium()
         .unwrap();
 
+    let texture = glium::texture::Texture2d::new(&display, image).unwrap();
+
     #[derive(Copy, Clone)]
     struct Vertex {
         position: [f32; 2],
+        tex_coords: [f32; 2],
     }
 
-    implement_vertex!(Vertex, position);
+    implement_vertex!(Vertex, position, tex_coords);
 
-    let vertex1 = Vertex { position: [-0.5, -0.5] };
-    let vertex2 = Vertex { position: [ 0.0,  0.5] };
-    let vertex3 = Vertex { position: [ 0.5, -0.25] };
+    let vertex1 = Vertex { position: [-0.5, -0.5], tex_coords: [0.0, 0.0] };
+    let vertex2 = Vertex { position: [ 0.0,  0.5], tex_coords: [0.5, 1.0] };
+    let vertex3 = Vertex { position: [ 0.5, -0.25], tex_coords: [1.0, 0.0]};
     let shape = vec![vertex1, vertex2, vertex3];
 
     let vertex_buffer = glium::VertexBuffer::new(&display, &shape).unwrap();
@@ -29,20 +40,22 @@ fn main() {
     let vertex_shader_src = r#"
         #version 140
         in vec2 position;
-        out vec2 my_attr;
+        in vec2 tex_coords;
+        out vec2 v_tex_coords;
         uniform mat4 trans;
         void main() {
-            my_attr = position;
+            v_tex_coords = tex_coords;
             gl_Position = trans * vec4(position, 0.0, 1.0);
         }
     "#;
 
     let fragment_shader_src = r#"
         #version 140
-        in vec2 my_attr;
+        in vec2 v_tex_coords;
         out vec4 color;
+        uniform sampler2D tex;
         void main() {
-            color = vec4(my_attr, 0.0, 1.0);
+            color = texture(tex, v_tex_coords);
         }
     "#;
 
@@ -52,17 +65,23 @@ fn main() {
     let mut t: f32 = -0.5;
     loop {
         t += 0.002;
-        if t > 0.5 {
+        if t > 1.5 {
             t = -0.5;
         }
+        let u: f32 = if t > 0.5 {
+            1.0 - t
+        } else {
+            t
+        };
 
         let uniforms = uniform! {
             trans: [
-                [t.cos(),  t.sin(), 0.0, 0.0],
-                [-t.sin(), t.cos(), 0.0, 0.0],
+                [u.cos(),  u.sin(), 0.0, 0.0],
+                [-u.sin(), u.cos(), 0.0, 0.0],
                 [1.0,      0.0,     1.0, 0.0],
-                [t,        0.0,     0.0, 1.0f32],
-            ]
+                [u,        0.0,     0.0, 1.0f32],
+            ],
+            tex: &texture,
         };
 
         let mut target = display.draw();
-- 
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