Uniform

Uniform是一种从CPU中的应用向GPU中的着色器发送数据的方式，一般会在每帧更新。

#shader fragment
#version 330 core  

layout(location = 0) out vec4 color;  

uniform vec4 u_Color;

void main()
{  
	color = u_Color;   
};

int location = glGetUniformLocation(shader, "u_Color");
ASSERT(location != -1);
GLCall(glUniform4f(location, 0.2f, 0.3f, 0.8f, 1.0f));

float r = 0.0f;
float increment = 0.05f;
/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
    /* Render here */
    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 */
    glfwSwapBuffers(window);
    /* Poll for and process events */
    glfwPollEvents();
}