绘制三角形条时，OpenGL会在原点添加不需要的顶点

Question

我的OpenGL应用程序中存在一个问题，OpenGL似乎在我的某些网格的原点添加了一个顶点。这个问题让我感到困惑，因为它似乎只影响由三角形条带组成的网格。在帖子末尾用于创建屏幕截图的基本过程如下：

1. 使用simple math生成位于单位球体上的顶点，以及纹理坐标和元素索引。
2. 将步骤1中的数据加载到绑定到VAO的缓冲区中。
3. 每一帧：绑定VAO并使用glDrawElements()
绘制

在发布之前，我在过程的每个阶段检查了我的网格的（简化版本）顶点数据，并且在原点（模型空间）中没有任何顶点。但是，如果您查看帖子末尾的屏幕截图，网格中心显然有一个顶点，它的存在会使我的网格变形并导致纹理问题。

我对3D图形缺乏经验，之前从未听说过这样的问题，所以我不确定我能提供哪些其他有用的信息。如果还有其他内容，请在评论中告诉我。

（地球的相同模型分别为GL_POINTS，GL_LINE_LOOP和GL_TRIANGLE_STRIP）

UPDATE：根据要求，这是设置和绘制顶点数组的代码：

public void init(GL3 gl){
    //If there is no graphics data, this object isn't going to get rendered and we should just leave
    if(gData == null){
        return;
    }

    //Prepare the index data
    short[] indexData = gData.getIndexArray();
    indexCount = indexData.length;

    //This is required because interleaving the data
    //screws with how the data is laid out in memory
    for(int i = 0; i < indexCount; i++){
        indexData[i] *= gData.getVertexData().size();
        indexData[i] = indexData[i] < 0 ? -1 : indexData[i]; 
    }

    //Put the program together
    glProgram = gl.glCreateProgram();
    for(Shader shader : gData.getShaders()){
        shader.compile(gl);
        gl.glAttachShader(glProgram, shader.location);
    }
    gl.glLinkProgram(glProgram);
    int[] result = new int[1];
    gl.glGetProgramiv(glProgram, GL3.GL_LINK_STATUS, result, 0);
    if(result[0] != GL3.GL_TRUE){
        byte[] info = new byte[512];
        gl.glGetProgramInfoLog(glProgram, 512, result, 0, info, 0);
        Logger.log(new String(info), Logger.ERROR, "GameObject -- init -- Link Error");
    }

    //Interleave the per-vertex data
    float[] vertexData = interleave(gData.getVertexData().toArray(new VertexData[0]));

    //Generate buffers
    gl.glGenVertexArrays(1, glBuffer, 0);
    gl.glGenBuffers(2, glBuffer, 1);
    if(checkGLErrors(gl, "After generating VAO and buffers")){
        sHandler.Quit();
    }

    //Bind the VAO, program, and buffers. In that order.
    gl.glBindVertexArray(glBuffer[0]);
    if(checkGLErrors(gl, "After binding VAO")){
        sHandler.Quit();
    }
    gl.glUseProgram(glProgram);
    if(checkGLErrors(gl, "After binding program")){
        sHandler.Quit();
    }
    gl.glBindBuffer(GL3.GL_ARRAY_BUFFER, glBuffer[1]);
    gl.glBindBuffer(GL3.GL_ELEMENT_ARRAY_BUFFER, glBuffer[2]);
    if(checkGLErrors(gl, "After binding buffers")){
        sHandler.Quit();
    }

    //Send in the per-vertex data
    gl.glBufferData(
            GL3.GL_ARRAY_BUFFER,
            vertexData.length * SIZEOF_FLOAT,
            FloatBuffer.wrap(vertexData),
            GL3.GL_STATIC_DRAW);
    if(checkGLErrors(gl, "After loading data into the buffers")){
        sHandler.Quit();
    }

    //Set up pointers to the vertex attributes
    for(VertexData a : gData.getVertexData()){
        a.location = gl.glGetAttribLocation(glProgram, a.name);
        gl.glVertexAttribPointer(a.location, a.components, GL3.GL_FLOAT, false, a.stride * SIZEOF_FLOAT, a.offset * SIZEOF_FLOAT);
        gl.glEnableVertexAttribArray(a.location);
        if(checkGLErrors(gl, "After setting pointers to the vertex attributes")){
            sHandler.Quit();
        }
    }

    //Set up pointers to the uniform variables
    for(UniformData uniform : gData.getUniformData()){
        uniform.location = gl.glGetUniformLocation(glProgram, uniform.name);
        if(checkGLErrors(gl, "After setting pointers to the uniform variables")){
            sHandler.Quit();
        }
    }

    //Send in index data
    gl.glBufferData(
            GL3.GL_ELEMENT_ARRAY_BUFFER, 
            indexData.length * SIZEOF_SHORT, 
            ShortBuffer.wrap(indexData), 
            GL3.GL_STATIC_DRAW);
    if(checkGLErrors(gl, "After loading in index data")){
        sHandler.Quit();
    }

    //Load textures
    for(int i = 0; i < glTextures.length; i++){
        glTextures[i] = gData.getTextureData().get(i).loadTexture(gl);
        if(checkGLErrors(gl, "After loading texture "+i)){
            sHandler.Quit();
        }
    }

    //Bind only the first texture....
    if(glTextures.length >= 1){
        gl.glBindTexture(GL3.GL_TEXTURE_2D, glTextures[0]);
        if(checkGLErrors(gl, "After binding textures")){
            sHandler.Quit();
        }
    }

    //-----BEGIN OPENGL STATE SETTINGS-----

    //Depth Testing
    gl.glEnable(GL3.GL_DEPTH_TEST);
    gl.glDepthFunc(GL3.GL_LEQUAL);

    //Primitive Restart
    gl.glEnable(GL3.GL_PRIMITIVE_RESTART);
    gl.glPrimitiveRestartIndex(-1);

    //Enlargen points
    gl.glPointSize(5.0f);

    //-----END OPENGL STATE SETTINGS-----

    //...And we're done here.
    gl.glBindVertexArray(0);

    if(checkGLErrors(gl, "After completing Object Initialization")){
        sHandler.Quit();
    }
}

public void draw(GL3 gl){
    //Check to see if this object actually needs to be drawn
    if(gData == null){
        return;
    }

    //Bind the vertex array
    gl.glBindVertexArray(glBuffer[0]);
    gl.glUseProgram(glProgram);
    checkGLErrors(gl, "After binding vertex array");

    //Load the uniform data
    for(UniformData uniform: gData.getUniformData()){
        uniform.loadData(gl);
    }
    checkGLErrors(gl, "After loading uniform data");

    //Draw
    gl.glDrawElements(gData.getPrimitive(), indexCount, GL3.GL_UNSIGNED_SHORT, 0);

    //Unbind
    gl.glBindVertexArray(0);

    checkGLErrors(gl, "After finishing draw");
}

Answer 1

  

gl.glPrimitiveRestartIndex（-1）;

这看起来不正确，因为the parameter to glPrimitiveRestartIndex是无符号的。结果是重启索引设置为4294967295。

  

gl.glDrawElements（gData.getPrimitive（），indexCount，GL3.GL_UNSIGNED_SHORT，0）;

在这里，指数是无符号的。 (GLuint)-1 != (GLushort)-1，因此VBO中的“重启”点不会导致重启，它们导致使用索引65535（超出数据范围）被视为（0,0,0）