Shader Uniform

Window_practice/src/Main.cpp

@@ -112,9 +112,7 @@ int main(void){
     }    
 
     //Main window creation
-    GLFWwindow* window;
+    GLFWwindow* window = glfwCreateWindow(640, 480, "OpenGl practice", NULL, NULL);
-
-    window = glfwCreateWindow(640, 480, "OpenGl practice", NULL, NULL);
     if (!window){
         std::cout << "Window could not be created!" << std::endl;
         glfwTerminate();
@@ -123,9 +121,11 @@ int main(void){
    
     glfwMakeContextCurrent(window);
 
+    glfwSwapInterval(1); //v-sync
+
     //GLEW init
     if (glewInit() != GLEW_OK) {
-        std::cout << "GLEW Error" << std::endl;
+        std::cout << "GLEW could not be initialized" << std::endl;
         return -1;
     }
 
@@ -169,15 +169,30 @@ int main(void){
     unsigned int shader = CreateShader(source.VertexSource, source.FragmentSource);
     glUseProgram(shader);
 
+    //need to bound a shader before this
+    GLCall(int location = glGetUniformLocation(shader, "u_Color")); //finding u_Color location
+    ASSERT(location != -1);
+    GLCall(glUniform4f(location, 0.8f, 0.3f, 0.8f, 1.0f));
+
     GLCall(glBindBuffer(GL_ARRAY_BUFFER, 0)); //unbinding the buffer
 
+    float r = 0.0f;
+    float increment = 0.05f;
    //Main loop
     while (!glfwWindowShouldClose(window)){
         /* Render here */
         GLCall(glClear(GL_COLOR_BUFFER_BIT));
 
+        GLCall(glUniform4f(location, r, 0.3f, 0.8f, 1.0f));
         GLCall(glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr));
 
+        if (r > 1.0f)
+            increment = -0.05f;
+        else if (r < 0.0f)
+            increment = 0.05f;
+
+        r += increment;
+
         /* Swap front and back buffers */
         GLCall(glfwSwapBuffers(window));