feat: add colors to vao and shaders

src/main.rs

@@ -59,7 +59,7 @@ fn offset<T>(n: u32) -> *const c_void {
 // Get a null pointer (equivalent to an offset of 0)
 // ptr::null()
 
-unsafe fn create_vao(vertices: &Vec<f32>, indices: &Vec<u32>) -> u32 {
+unsafe fn create_vao(vertices: &Vec<f32>, colors: &Vec<f32>, indices: &Vec<u32>) -> u32 {
     let mut vao_id = 0;
     gl::GenVertexArrays(1, &mut vao_id);
     gl::BindVertexArray(vao_id);
@@ -95,6 +95,26 @@ unsafe fn create_vao(vertices: &Vec<f32>, indices: &Vec<u32>) -> u32 {
         gl::STATIC_DRAW,
     );
 
+    // color buffer
+    let mut cbo_id = 0;
+    gl::GenBuffers(1, &mut cbo_id);
+    gl::BindBuffer(gl::ARRAY_BUFFER, cbo_id);
+    gl::BufferData(
+        gl::ARRAY_BUFFER,
+        byte_size_of_array(&colors),
+        colors.as_ptr() as *const c_void,
+        gl::STATIC_DRAW,
+    );
+    gl::VertexAttribPointer(
+        1,
+        4,
+        gl::FLOAT,
+        gl::FALSE,
+        0,
+        std::ptr::null(),
+    );
+    gl::EnableVertexAttribArray(1);
+
     vao_id
 }
 
@@ -170,7 +190,12 @@ fn main() {
 
         let vertices = vec![-0.6, -0.6, 0., 0.6, -0.6, 0., 0., 0.6, 0.];
         let indices = vec![0, 1, 2];
-        let my_vao = unsafe { create_vao(&vertices, &indices) };
+        let colors  = vec![
+            1.0, 0.0, 0.0, 1.0,  // vertex 1: red
+            0.0, 1.0, 0.0, 1.0,  // vertex 2: green
+            0.0, 0.0, 1.0, 1.0,  // vertex 3: blue
+        ];
+        let my_vao = unsafe { create_vao(&vertices, &colors, &indices) };
 
         // == // Set up your shaders here