为什么此代码在 LWJGL 3 中不显示三角形?

Why doesn't this code show a triangle in LWJGL 3?

我正在尝试制作游戏引擎,但我卡在了三角形步骤上。由于我目前的代码有多个class,我试图将其简化为一个class。

public class MainGame {

    public static void main(String[] args) {
        GLFW.glfwInit();
        
        GLFW.glfwWindowHint(GLFW.GLFW_CONTEXT_VERSION_MAJOR, 4);
        GLFW.glfwWindowHint(GLFW.GLFW_CONTEXT_VERSION_MINOR, 0);
        GLFW.glfwWindowHint(GLFW.GLFW_OPENGL_PROFILE, GLFW.GLFW_OPENGL_CORE_PROFILE);
        
        long window = GLFW.glfwCreateWindow(900, 900, "Test Window", NULL, NULL);
        
        GLFWVidMode vid = GLFW.glfwGetVideoMode(GLFW.glfwGetPrimaryMonitor());
        GLFW.glfwSetWindowPos(window, (vid.width() - 900)/2, 
                (vid.height() - 900)/2);
        
        GLFW.glfwMakeContextCurrent(window);
        
        GL.createCapabilities();
        
        GLFW.glfwSwapInterval(1);
        GLFW.glfwShowWindow(window);
        
        int programId = 0;
        try {
            programId = loadProgram("triangle.vert.glsl", "triangle.frag.glsl");
        } catch (IOException e) {
            e.printStackTrace();
        }
        int vaoId = loadTriangle();
        while (!GLFW.glfwWindowShouldClose(window)) {
            GL11.glClear(GL11.GL_COLOR_BUFFER_BIT);
            GL11.glClearColor(1, 0, 0, 1);
            GLFW.glfwSwapBuffers(window); 
            GLFW.glfwPollEvents();
            
            GL30.glUseProgram(programId);
            GL30.glBindVertexArray(vaoId);
            GL20.glEnableVertexAttribArray(0);
            GL11.glDrawArrays(GL11.GL_TRIANGLES, 0, 3);
            GL20.glDisableVertexAttribArray(0);
            GL30.glBindVertexArray(0);
            GL30.glUseProgram(0);
        }
        
        GL30.glDeleteVertexArrays(vaoId);
        GL30.glDeleteProgram(programId);
        GLFW.glfwDestroyWindow(window);
        GLFW.glfwTerminate();
        
    }
    
    private static int loadTriangle() {

        float[] positions = new float[] {
            +0f, +1f,
            -1f, -1f,
            +1f, -1f
        };
        
        FloatBuffer buffer = BufferUtils.createFloatBuffer(positions.length);
        buffer.put(positions);
        buffer.flip();

        int vaoId = GL30.glGenVertexArrays();
        GL30.glBindVertexArray(vaoId);
        
        int bufferId = GL15.glGenBuffers();
        GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, bufferId);
        GL15.glBufferData(GL15.GL_ARRAY_BUFFER, buffer, GL15.GL_STATIC_DRAW);
        GL20.glVertexAttribPointer(0, 2, GL11.GL_FLOAT, false, 0, 0);
        
        GL30.glBindVertexArray(0);
        
        return vaoId;
    } 
    
    private static int loadProgram(String vertex, String fragment) throws IOException {
        int vertexShader = GL30.glCreateShader(GL30.GL_VERTEX_SHADER);
        int fragmentShader = GL30.glCreateShader(GL30.GL_FRAGMENT_SHADER);

        String vertexCode = Files.lines(Paths.get(vertex))
                .collect(Collectors.joining("\n"));

        String fragmentCode = Files.lines(Paths.get(fragment))
                .collect(Collectors.joining("\n"));
        
        GL30.glShaderSource(vertexShader, vertexCode);
        GL30.glCompileShader(vertexShader);
        String slog = GL30.glGetShaderInfoLog(vertexShader);
        System.out.println(slog);
        
        GL30.glShaderSource(fragmentShader, fragmentCode);
        GL30.glCompileShader(fragmentShader);
        slog = GL30.glGetShaderInfoLog(fragmentShader);
        System.out.println(slog);

        int program = GL30.glCreateProgram();
        GL30.glAttachShader(program, vertexShader);
        GL30.glAttachShader(program, fragmentShader);
        GL30.glLinkProgram(program);

        GL30.glDetachShader(program, vertexShader);
        GL30.glDetachShader(program, fragmentShader);

        GL30.glDeleteShader(vertexShader);
        GL30.glDeleteShader(fragmentShader);
        
        return program;
    }

}

这是triangle.vert.glsl:

#version 400 core
layout(location = 0) in vec2 position;
void main() {
  gl_Position = vec4(position, 0.0, 1.0);
}

这是triangle.frag.glsl:

#version 400 core
out vec4 color;
void main() {
  color = vec4(0.0, 0.0, 1.0, 1.0);
}

当我运行程序时,没有OpenGL或GLSL错误。我尝试使用 glGetError() 但一切都是 0.

我希望看到一个红色背景的蓝色三角形,但我只有一个红色 window。我相当确定问题不在于 GLFW 代码( window 确实出现)或着色器代码(着色器确实编译并且当我在着色器代码中出错时,程序将其列为这样的)。不过三角码好像也还行

有什么我遗漏或弄错的吗?

注意:我只在一台计算机上测试过,所以这可能是计算机特定的错误。

循环中每帧的操作顺序错误。

如果我们查看一帧期间发生的情况(从交换缓冲区到交换缓冲区间隔),那么本质上,您首先执行渲染三角形的绘制调用,然后再次清除颜色缓冲区(这将覆盖您的三角形使用清晰的颜色)和然后你交换缓冲区。

所以,现在,每帧的操作顺序总是:

  1. 平局
  2. 清除缓冲区
  3. 交换缓冲区

为了解决这个问题,您应该将交换缓冲区调用 glfwSwapBuffers(window) 放在循环的末尾,这会将每帧的操作顺序更改为:

  1. 清除缓冲区
  2. 平局
  3. 交换缓冲区

然后你会看到蓝色三角形。