vertex colours

res/shader/shader.frag

@@ -1,9 +1,9 @@
 #version 330 core
 out vec4 FragColor;
 
-uniform vec4 ourColor;
+in vec3 ourColor;
 
 void main()
 {
-    FragColor = ourColor;
+    FragColor = vec4(ourColor, 1.0);
 }

res/shader/shader.vert

@@ -1,10 +1,11 @@
 #version 330 core
-layout (location = 0) in vec3 aPos;
+layout (location = 0) in vec3 aPos;     // position has attribute position 0
+layout (location = 1) in vec3 aColor;   // color has attribute position 1
 
-out vec4 vertexColor;
+out vec3 ourColor;
 
 void main()
 {
-    gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
-    vertexColor = vec4(0.5, 0.0, 0.0, 1.0);
+    gl_Position = vec4(aPos, 1.0);
+    ourColor = aColor;
 }

src/main.c

@@ -3,10 +3,11 @@
 #include "gfx.h"
 
 float vertices[] = {
-     0.5f,  0.5f,  0.0f, // top right
-     0.5f, -0.5f,  0.0f, // bottom right
-    -0.5f, -0.5f,  0.0f, // bottom left
-    -0.5f,  0.5f,  0.0f  // top left
+    // position             color
+     0.5f,  0.5f,  0.0f,    1.0f, 1.0f, 1.0f,  // top right
+     0.5f, -0.5f,  0.0f,    1.0f, 0.0f, 0.0f,  // bottom right
+    -0.5f, -0.5f,  0.0f,    0.0f, 1.0f, 0.0f,  // bottom left
+    -0.5f,  0.5f,  0.0f,    0.0f, 0.0f, 1.0f   // top left
 };
 
 unsigned int indices[] = {
@@ -50,8 +51,13 @@ int main()
     glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
 
     // set vertex attributes
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3*sizeof(float), (void*)0); // TODO: wtf
+
+    // position attribute
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6*sizeof(float), (void*)0); // TODO: wtf
     glEnableVertexAttribArray(0);
+    // color attribute
+    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6*sizeof(float), (void*)(3 * sizeof(float)));
+    glEnableVertexAttribArray(1);
 
     glUseProgram(shaderProgram);