Question

我已经从lwjgl.org网页（http://www.lwjgl.org/guide）编译了Get Started示例，现在我想继续更改为背景颜色。所以，我想要一些像闪烁效果的东西。但是，当程序运行时，我无法使用glClearColor永久地切换其颜色。我试图在glClearColor的while循环中的loop（）函数中执行此操作。但这似乎是错误的，因为glClearColor方法只在while循环之外调用。例如，在下面的代码中，背景颜色采用最后使用glClearColor调用的颜色。

...
 private void loop() {
    // This line is critical for LWJGL's interoperation with GLFW's
    // OpenGL context, or any context that is managed externally.
    // LWJGL detects the context that is current in the current thread,
    // creates the ContextCapabilities instance and makes the OpenGL
    // bindings available for use.
    GLContext.createFromCurrent();



    // Set the clear color
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

    // Run the rendering loop until the user has attempted to close
    // the window or has pressed the ESCAPE key.
    while ( glfwWindowShouldClose(window) == GL_FALSE ) {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // clear the framebuffer

        /* Switch permanently between red and green background color
            - doesn't work, no blinking, just green background color */ 
        glClearColor(1.0f, 0.0f, 0.0f, 0.0f);
        glClearColor(0.0f, 1.0f, 0.0f, 0.0f);

        glfwSwapBuffers(window); // swap the color buffers

        // Poll for window events. The key callback above will only be
        // invoked during this call.
        glfwPollEvents();
    }
}
...

我对lwjgl很新，因此我认为我犯了一些基本的错误，背景颜色不应该像我那样改变。有没有办法处理lwjgl中的背景来实现这个目标？

我应该提到我正在使用lwjgl 3，而不是lwjgl 2.而且似乎没有显示类了。 GLFW似乎是它的替代品。

Answer 1

在下面的while循环中，假设每次迭代代表你的1帧。在场景中，只有在每次迭代后glfwPollEvents()调用后才会看到更改。这就是为什么在一次迭代中改变颜色2次不会影响任何事情。

while ( glfwWindowShouldClose(window) == GL_FALSE ) {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // clear the framebuffer

    /* Switch permanently between red and green background color
        - doesn't work, no blinking, just green background color */ 
    glClearColor(1.0f, 0.0f, 0.0f, 0.0f);
    glClearColor(0.0f, 1.0f, 0.0f, 0.0f);

    glfwSwapBuffers(window); // swap the color buffers

    // Poll for window events. The key callback above will only be
    // invoked during this call.
    glfwPollEvents();
}

在下面，我为您的问题编写了一个简单的解决方案。如果你改变每一帧的颜色你都看不到变化，因为它会非常快，所以我做了一个小技巧，每30帧改变你的颜色。您可以使用时间相关的颜色变化而不是帧数来编写替代方案。

正确版本：

boolean redOrGreen = true; // true = Green false = Red
int  counter = 0;
int  COLORCHANGEAT = 30;

while ( glfwWindowShouldClose(window) == GL_FALSE ) {

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // clear the framebuffer

    counter++;
    if(counter == COLORCHANGEAT) {      
       redOrGreen = !redOrGreen;
       counter = counter % COLORCHANGEAT;
    }

    if(redOrGreen == true)
       glClearColor(1.0f, 1.0f, 0.0f, 0.0f);
    else        
       glClearColor(0.0f, 1.0f, 0.0f, 0.0f);

    glfwSwapBuffers(window); // swap the color buffers

    // Poll for window events. The key callback above will only be
    // invoked during this call.
    glfwPollEvents();
}

使用lwjgl使背景闪烁

1 个答案: