OpenGL 生成三角形网格

Question

我是 OpenGl 的初学者，我正尝试在 OpenGL 中绘制三角形网格，例如 this，我的问题是它没有绘制，我不明白为什么。此外，如果我打印顶点数组，则所有顶点的 x 和 y 坐标保持不变。 x 和 z 坐标都应位于 +1 和 -1 之间。当 m_meshResolution = 1 时，坐标似乎是正确的，但在其他情况下则不然。我认为有一种更简单的方法可以尝试执行此操作，因此欢迎所有建议。

int size = m_meshResolution * m_meshResolution * 2 * 3 * 3;
float* positions = new float[size]();

double triangleWidth = 2 / m_meshResolution;
float startX = -1.0f;
float startZ = 1.0f;
float x1 = 0;
float x2 = 0;
float z1 = 0;
float z2 = 0;
int index = 0;
//For each row
for (int r = 0; r < m_meshResolution; r++) {
    //For each column
    for (int c = 0; c < m_meshResolution; c++) {
        x1 = startX + c*divider;
        x2 = startX + (c+1)*divider;
        z1 = startZ - r*divider;
        z2 = startZ -(r+1)*divider;
        //Generate one triangle
        positions[index++] = x1;
        positions[index++] = 0;
        positions[index++] = z1;
        positions[index++] = x2;
        positions[index++] = 0;
        positions[index++] = z2;
        positions[index++] = x2;
        positions[index++] = 0;
        positions[index++] = z1;
        //Generate other triangle
        positions[index++] = x1;
        positions[index++] = 0;
        positions[index++] = z1;
        positions[index++] = x1;
        positions[index++] = 0;
        positions[index++] = z2;
        positions[index++] = x2;
        positions[index++] = 0;
        positions[index++] = z2;
    }

//Set buffers
glGenBuffers(1, &m_positionBuffer);
glBindBuffer(GL_ARRAY_BUFFER, m_positionBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

glGenVertexArrays(1, &m_vao);
glBindVertexArray(m_vao);
glBindBuffer(GL_ARRAY_BUFFER, m_positionBuffer);
glVertexAttribPointer(0, 3, GL_FLOAT, false/*normalized*/, 0/*stride*/, 0/*offset*/);
glEnableVertexAttribArray(0);

//Draw
glBindVertexArray(m_vao);
glDrawArrays(GL_TRIANGLES, 0, m_meshResolution*m_meshResolution*2*3);

Answer 1

positions是一个指针，而sizeof(positions)returns4或8个字节，这取决于体系结构，但是glBufferData的第二个参数告诉我们

size Specifies the size in bytes of the buffer object's new data store.

你应该使用 sizeof(float) * size 作为第二个参数。

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