如何在 3D 中绘制 2D 网格？

Question

我正在尝试绘制带有三角形网格的简单 "floor"，但只绘制了其中的四分之一。例如，这里是 5 x 5 网格尝试的屏幕截图：

我画了几个不同的M x N格子，好像每次都画⌊(MxN)/4⌋个正方形。

因此，对于 5 x 5 网格：

int QUAD_DEPTH = 5;
int QUAD_WIDTH = 5;
std::vector<GLfloat> vertices;

我正在加载一个矢量；每个顶点六个浮点数 (XYZRGB)，每个三角形三个顶点，每个正方形两个三角形：

for (int row = 0; row < QUAD_WIDTH; row++) {
  for (int dist = 0; dist < QUAD_DEPTH; dist++) {
    vertices.push_back(0.0f + row); // X
    vertices.push_back(0.0f); // Y
    vertices.push_back(0.0f + dist); // Z
    vertices.push_back(1.0f); // R
    vertices.push_back(0.0f); // G
    vertices.push_back(0.0f); // B

    vertices.push_back(1.0f + row); // X
    vertices.push_back(0.0f); // Y
    vertices.push_back(1.0f + dist); // Z
    vertices.push_back(0.0f); // R
    vertices.push_back(1.0f); // G
    vertices.push_back(0.0f); // B

    vertices.push_back(1.0f + row); // X
    vertices.push_back(0.0f); // Y
    vertices.push_back(0.0f + dist); // Z
    vertices.push_back(0.0f); // R
    vertices.push_back(0.0f); // G
    vertices.push_back(1.0f); // B

    vertices.push_back(0.0f + row); // X
    vertices.push_back(0.0f); // Y
    vertices.push_back(0.0f + dist); // Z
    vertices.push_back(1.0f); // R
    vertices.push_back(0.0f); // G
    vertices.push_back(0.0f); // B

    vertices.push_back(0.0f + row); // X
    vertices.push_back(0.0f); // Y
    vertices.push_back(1.0f + dist); // Z
    vertices.push_back(0.0f); // R
    vertices.push_back(1.0f); // G
    vertices.push_back(0.0f); // B

    vertices.push_back(1.0f + row); // X
    vertices.push_back(0.0f); // Y
    vertices.push_back(1.0f + dist); // Z
    vertices.push_back(0.0f); // R
    vertices.push_back(0.0f); // G
    vertices.push_back(1.0f); // B
  }
}

然后我缓冲浮点数：

glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);

glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, vertices.size(), &vertices[0], GL_STATIC_DRAW);

glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(0);

glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
glEnableVertexAttribArray(1);

glBindVertexArray(0);

然后画出来：

glBindVertexArray(VAO);
glUniformMatrix4fv(glGetUniformLocation(this->shader->Program, "projection"), 1, GL_FALSE, &projection[0][0]);
glUniformMatrix4fv(glGetUniformLocation(this->shader->Program, "view"), 1, GL_FALSE, &view[0][0]);
glUniformMatrix4fv(glGetUniformLocation(this->shader->Program, "model"), 1, GL_FALSE, &this->model_matrix[0][0]);
glDrawArrays(GL_TRIANGLES, 0, vertices.size());
glBindVertexArray(0);

我也尝试了 glDrawArrays(GL_TRIANGLES, 0, vertices.size() / 6); 因为每个顶点有六个浮点数，但结果相同。

我缓冲不正确或绘图不正确还是我的问题在其他地方？

Answer 1

问题出在您对 glBufferData() 的调用上：

glBufferData(GL_ARRAY_BUFFER, vertices.size(), &vertices[0], GL_STATIC_DRAW);

第二个参数是以字节为单位的大小，同时您在向量中传递浮点数。您需要将向量的大小乘以浮点数的大小以获得以字节为单位的大小。例如：

glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(vertices[0]), &vertices[0], GL_STATIC_DRAW);

如何在 3D 中绘制 2D 网格？

How can I draw a 2D grid in 3D?

c++

opengl

vector

std