Question

我只是复制粘贴了来自this tutorial的LWJGL维基上的代码，为了您的方便，我现在将其粘贴在这里。

import org.lwjgl.BufferUtils;
import org.lwjgl.LWJGLException;
import org.lwjgl.opengl.*;
import org.lwjgl.util.glu.GLU;

import java.nio.FloatBuffer;

public class TheQuadExampleDrawArrays {
  // Entry point for the application
  public static void main(String[] args) {
    new TheQuadExampleDrawArrays();
  }

  // Setup variables
  private final String WINDOW_TITLE = "The Quad: glDrawArrays";
  private final int WIDTH = 320;
  private final int HEIGHT = 240;
  // Quad variables
  private int vaoId = 0;
  private int vboId = 0;
  private int vertexCount = 0;

  public TheQuadExampleDrawArrays() {
    // Initialize OpenGL (Display)
    this.setupOpenGL();

    this.setupQuad();

    while (!Display.isCloseRequested()) {
      // Do a single loop (logic/render)
      this.loopCycle();

      // Force a maximum FPS of about 60
      Display.sync(60);
      // Let the CPU synchronize with the GPU if GPU is tagging behind
      Display.update();
    }

    // Destroy OpenGL (Display)
    this.destroyOpenGL();
  }

  public void setupOpenGL() {
    // Setup an OpenGL context with API version 3.2
    try {
      PixelFormat pixelFormat = new PixelFormat();
      ContextAttribs contextAtrributes = new ContextAttribs(3, 2)
        .withForwardCompatible(true)
        .withProfileCore(true);

      Display.setDisplayMode(new DisplayMode(WIDTH, HEIGHT));
      Display.setTitle(WINDOW_TITLE);
      Display.create(pixelFormat, contextAtrributes);

      GL11.glViewport(0, 0, WIDTH, HEIGHT);
    } catch (LWJGLException e) {
      e.printStackTrace();
      System.exit(-1);
    }

    // Setup an XNA like background color
    GL11.glClearColor(0.4f, 0.6f, 0.9f, 0f);

    // Map the internal OpenGL coordinate system to the entire screen
    GL11.glViewport(0, 0, WIDTH, HEIGHT);

    this.exitOnGLError("Error in setupOpenGL");
  }

  public void setupQuad() {
    // OpenGL expects vertices to be defined counter clockwise by default
    float[] vertices = {
      // Left bottom triangle
      -0.5f, 0.5f, 0f,
      -0.5f, -0.5f, 0f,
      0.5f, -0.5f, 0f,
      // Right top triangle
      0.5f, -0.5f, 0f,
      0.5f, 0.5f, 0f,
      -0.5f, 0.5f, 0f
    };
    // Sending data to OpenGL requires the usage of (flipped) byte buffers
    FloatBuffer verticesBuffer = BufferUtils.createFloatBuffer(vertices.length);
    verticesBuffer.put(vertices);
    verticesBuffer.flip();

    vertexCount = 6;

    // Create a new Vertex Array Object in memory and select it (bind)
    // A VAO can have up to 16 attributes (VBO's) assigned to it by default
    vaoId = GL30.glGenVertexArrays();
    GL30.glBindVertexArray(vaoId);

    // Create a new Vertex Buffer Object in memory and select it (bind)
    // A VBO is a collection of Vectors which in this case resemble the location of each vertex.
    vboId = GL15.glGenBuffers();
    GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vboId);
    GL15.glBufferData(GL15.GL_ARRAY_BUFFER, verticesBuffer, GL15.GL_STATIC_DRAW);
    // Put the VBO in the attributes list at index 0
    GL20.glVertexAttribPointer(0, 3, GL11.GL_FLOAT, false, 0, 0);
    // Deselect (bind to 0) the VBO
    GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0);

    // Deselect (bind to 0) the VAO
    GL30.glBindVertexArray(0);

    this.exitOnGLError("Error in setupQuad");
  }

  public void loopCycle() {
    GL11.glClear(GL11.GL_COLOR_BUFFER_BIT);

    // Bind to the VAO that has all the information about the quad vertices
    GL30.glBindVertexArray(vaoId);
    GL20.glEnableVertexAttribArray(0);

    // Draw the vertices
    GL11.glDrawArrays(GL11.GL_TRIANGLES, 0, vertexCount);
    /**
     * !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
     * I found that the GL_INVALID_OPERATION flag was being raised here,
     * at the call to glDrawArrays().
     * !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
     */

    // Put everything back to default (deselect)
    GL20.glDisableVertexAttribArray(0);
    GL30.glBindVertexArray(0);

    this.exitOnGLError("Error in loopCycle");
  }

  public void destroyOpenGL() {
    // Disable the VBO index from the VAO attributes list
    GL20.glDisableVertexAttribArray(0);

    // Delete the VBO
    GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0);
    GL15.glDeleteBuffers(vboId);

    // Delete the VAO
    GL30.glBindVertexArray(0);
    GL30.glDeleteVertexArrays(vaoId);

    Display.destroy();
  }

  public void exitOnGLError(String errorMessage) {
    int errorValue = GL11.glGetError();

    if (errorValue != GL11.GL_NO_ERROR) {
      String errorString = GLU.gluErrorString(errorValue);
      System.err.println("ERROR - " + errorMessage + ": " + errorString);

      if (Display.isCreated()) Display.destroy();
      System.exit(-1);
    }
  }
}

当我运行它时，它抛出了一个错误

ERROR - Error in loopCycle: Invalid operation

我将其缩小到glDrawArrays()方法中对loopCycle()的调用，然后点击谷歌找出可能意味着什么，并发现this SO question，其中列出了整整可能的原因（为方便起见，这里列出）。

GL_INVALID_OPERATION

GL_DRAW_INDIRECT_BUFFER。

GL_INVALID_OPERATION

glDrawArrays

glBegin

glEnd。
GL_INVALID_OPERATION将由glDrawArrays或glDrawElements生成，如果当前程序对象中的任何两个活动采样器具有不同类型，但引用相同的纹理图像单元。
GL_INVALID_OPERATION。

GL_INVALID_OPERATION

GL_PATCHES。
GL_INVALID_OPERATION，这将导致超出任何缓冲区对象大小的限制，或超出结束位置偏移+ size - 1，由glBindBufferRange设置。
GL_INVALID_OPERATION由glDrawArrays()生成，如果没有几何着色器，则转换反馈处于活动状态且模式不是允许的模式之一。
GL_INVALID_OPERATION由glDrawArrays()生成，如果存在几何着色器，则变换反馈处于活动状态，并且几何着色器的输出基本类型与变换反馈primitiveMode不匹配。
GL_INVALID_OPERATION。
GL_INVALID_OPERATION，并且绑定到变换反馈绑定点的缓冲区也绑定到数组缓冲区绑定点。

这些对我来说没有任何意义，经过相当长的时间阅读它们之后，我就无法找到这段代码的错误。如果有人比我更了解这个，请指出GL_INVALID_OPERATION旗帜被提出的原因吗？

Answer 1

项目9.看起来您没有绑定着色器程序。

您正在使用核心配置文件创建上下文：

  ContextAttribs contextAtrributes = new ContextAttribs(3, 2)
    .withForwardCompatible(true)
    .withProfileCore(true);

使用核心配置文件，您需要提供着色器程序。您通常会在GLSL中至少编写一个顶点和一个片段着色器，然后使用以下调用来构建和绑定着色器程序：

glCreateShader
glShaderSource
glCompileShader
glCreateProgram
glAttachShader
glLinkProgram
glUseProgram

LWJGL wiki上的示例代码因GL_INVALID_OPERATION而失败

1 个答案: