Question

我glDrawElements一致地工作，最初是一个简单的盒子，然后是由大量顶点组成的更复杂的形状。然后它只是停止绘制网格。我把代码带回了它最基本的代码，只绘制了2个三角形来制作2D正方形。这也不再适用。

void createMesh(void) {
    float vertices[12];
    vertices[0] = -0.5; vertices[1] = -0.5; vertices[2] = 0.0; // Bottom left corner
    vertices[3] = -0.5; vertices[4] = 0.5; vertices[5] = 0.0; // Top left corner
    vertices[6] = 0.5; vertices[7] = 0.5; vertices[8] = 0.0; // Top Right corner
    vertices[9] = 0.5; vertices[10] = -0.5; vertices[11] = 0.0; // Bottom right corner

    short indices[] = { 0, 1, 2, 0, 2, 3};

    glEnableClientState(GL_VERTEX_ARRAY);        // Enable Vertex Arrays

    glVertexPointer(3, GL_FLOAT, 0, vertices); // Set The Vertex Pointer To Our Vertex Data

    glDrawElements(GL_TRIANGLES,6 , GL_UNSIGNED_SHORT, indices); 

    glDisableClientState(GL_VERTEX_ARRAY);
}

以前显示的高级代码如下所示：

void createMesh(void) {
float vertices[(amountOfHorizontalScans * 480 * 3)];// Amount of vertices
    //build the array of vertices from a matrix of data
    int currentVertex = -1;
    std::vector <std::vector<double>> currentPointCloudMatrix = distanceCalculator.getPointCloudMatrix();
    double plotY = 0;
    double plotX = 0;
    for (int j = 0; j < currentPointCloudMatrix.size(); j++){
        std::vector <double> singleDistancesVector = currentPointCloudMatrix.at(j); 
        for (int i = 0; i < singleDistancesVector.size(); i++){
            if (singleDistancesVector.at(i) != 0){
                vertices[++currentVertex] = plotX;
                vertices[++currentVertex] = plotY;
                vertices[++currentVertex] = singleDistancesVector.at(i);
            }
            plotX += 0.1;
        }
        plotX = 0;
        plotY += 0.2; //increment y by 0.02     
    }

    //Creating the array of indices, 480 is the amount of columns
    int i = 0;
    short indices2[(amountOfHorizontalScans * 480 * 3)];
    for (int row = 0; row<amountOfHorizontalScans - 1; row++) {
        if ((row & 1) == 0) { // even rows
            for (int col = 0; col<480; col++) {
                indices2[i++] = col + row * 480;
                indices2[i++] = col + (row + 1) * 480;
            }
        }
        else { // odd rows
            for (int col = 480 - 1; col>0; col--) {
                indices2[i++] = col + (row + 1) * 480;
                indices2[i++] = col - 1 + +row * 480;
            }
        }
    }

    glEnableClientState(GL_VERTEX_ARRAY);        // Enable Vertex Arrays

    glVertexPointer(3, GL_FLOAT, 0, vertices); // Set The Vertex Pointer To Our Vertex Data

    glDrawElements(GL_TRIANGLE_STRIP, (amountOfHorizontalScans * 480 * 3), GL_UNSIGNED_SHORT, indices2);

    glDisableClientState(GL_VERTEX_ARRAY);
}

我完全失去了它为什么停止工作，因为它完美地运行了大量的运行，然后完全停止了。我已经调试过并且所有代码都已到达，顶点和索引也填充了数据。什么可能导致它停止工作？

编辑：所以我现在真的很困惑。今天早上我回到了这个问题，一切都恢复正常，因为在网格中没有任何问题。经过一些测试并运行程序多次，它只是停止再次绘制网格！

这可能与记忆有关吗？我不是100％肯定glDrawElements如何存储传递给它的数据，那么我是否必须清除一些我一直在填充数据的地方？

Answer 1

您无法在堆栈中动态分配数组：

short indices2[(amountOfHorizontalScans * 480 * 3)];

在代码中：

short indices2[(amountOfHorizontalScans * 480 * 3)];
for (int row = 0; row<amountOfHorizontalScans - 1; row++) {
    if ((row & 1) == 0) { // even rows
        for (int col = 0; col<480; col++) {
            indices2[i++] = col + row * 480;
            indices2[i++] = col + (row + 1) * 480;
        }
    }
    else { // odd rows
        for (int col = 480 - 1; col>0; col--) {
            indices2[i++] = col + (row + 1) * 480;
            indices2[i++] = col - 1 + +row * 480;
        }
    }
}

必须

short* indices2 = new short[(amountOfHorizontalScans * 480 * 3)];

比免费分配的内存

delete [] indices2;

Triangle strip非常棘手，您尝试直接使用GL_TRIANGLES。

glDrawElements已停止工作

1 个答案: