使用gl_VertexID计算顶点（在网格内）的X和Z位置

Question

我正在尝试生成3D地形。我的目标是将顶点着色器的高度传递给顶点着色器，并使用gl_VertexID从顶点着色器中计算x和z位置。顶点在x和z轴上相距1。这是顶点着色器：

#version 330 core

uniform mat4 projection;
uniform mat4 view;
uniform mat4 world;

layout(location = 0) in float height;

// vertex offset; position of vertex relative to the top left corner of square
const vec2 offset[6] = vec2[](
    vec2(0, 0), // top left
    vec2(0, 1), // bottom left
    vec2(1, 1), // bottom right
    vec2(1, 1), // bottom right
    vec2(0, 0), // top left
    vec2(1, 0)  // top right
);

void main() {
    // index of square
    int squareIndex = gl_VertexID / 6;
    // index of vertex within square
    int vertexIndex = gl_VertexID % 6;

    // xz position of vertex
    vec2 position = offset[vertexIndex] + vec2(squareIndex % LENGTH, squareIndex / LENGTH);

    gl_Position = projection * view * world * vec4(position.x, height, position.y, 1.0f);
}

三角形是从左到右，从上到下绘制的。这是EBO的生成：

for(unsigned int xSquare = 0; xSquare < LENGTH; xSquare++) {
   for(unsigned int zSquare = 0; zSquare < LENGTH; zSquare++) {
      size_t squareIndex = zSquare * LENGTH + xSquare;
      unsigned int topLeft = squareIndex;
      unsigned int topRight = squareIndex + 1;
      unsigned int bottomLeft = squareIndex + LENGTH;
      unsigned int bottomRight = squareIndex + LENGTH + 1;
      elements[squareIndex] = topLeft;
      elements[squareIndex + 1] = bottomLeft;
      elements[squareIndex + 2] = bottomRight;
      elements[squareIndex + 3] = bottomRight;
      elements[squareIndex + 4] = topLeft;
      elements[squareIndex + 5] = topRight;
   }
}

我已经使用qrenderdoc检查了顶点数据输入，并且高度已正确传递到顶点着色器。然而，the rendered output looks like this.

我已经检查了顶点着色器的逻辑，但没有发现任何问题。有人知道我在做什么错吗？

Answer 1

切片数不等于行或列中的点数，在点上比切片多。

因此可能必须是：

vec2 position = offset[vertexIndex] + 
                vec2(squareIndex % (LENGTH-1), squareIndex / (LENGTH-1));