fragment shader changes

pog.cpp

@@ -73,7 +73,7 @@ int main() {
     std::cout << "Vertex shader is gOOd!" << std::endl;
   const char *fragmentShaderSource =
       "#version 330 core\n"
-      "in vec3 aPos;\n"
+      "layout (location = 0) in vec3 aPos;\n"
       "out vec4 FragColor;\n"
       "void main()\n"
       "{\n"
@@ -138,6 +138,7 @@ int main() {
     // render
     // ------
     glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+    // glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
     glClear(GL_COLOR_BUFFER_BIT);
 
     // draw our first triangle