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我正在尝试使用 OpenGL 制作飞机，在某种程度上代码有效，但我在某些索引上得到了奇怪的结果。我会尽力解释我的代码，它是我的代码和我在网上找到的代码的混合体。

主要的：

所有设置都发生在 main 中，因此该函数将知道所有需要的值

float zoom = 6.0f;
float vertical = 1.2f;
float horizontal = 1.2f;

const int planeWidth = 4;  //columns
const int planeHeight = 2; //rows

const int totalVertices = (planeWidth + 1) * (planeHeight + 1);

//GLfloat* vertices = new GLfloat[totalVertices];
GLfloat vertices[totalVertices] = { 0.0 };

const int indPerRow = planeWidth * 2 + 2;
const int indDegenReq = (planeHeight - 1) * 2;
const int totalIndices = indPerRow * planeWidth + indDegenReq;

//GLuint* indices = new GLuint[totalIndices];
GLuint indices[totalIndices] = { 0 };

GLfloat texCoords[totalVertices] = { 0 };

makePlane(planeWidth, planeHeight, vertices, indices, texCoords);

功能：

第一个 for 循环创建顶点，第二个创建索引

void makePlane(int width, int height, GLfloat *vertices, GLuint *indices)
{
width++;  //columns
height++; //rows

int size = sizeof(GLfloat);
for (int y = 0; y < height; y++)
{
    int base = y * width;
    for (int x = 0; x < width; x++)
    {
        int index = (base + x) * 2;
        vertices[index]    = (float)x;
        vertices[index +1] = (float)y;
    }
}

int i = 0;
height--;

for (int y = 0; y < height; y++)
{
    int base = y * width;

    for (int x = 0; x < width; x++)
    {
        indices[i++] = base + x;
        indices[i++] = base + width + x; 
    }
    if (y < height - 1)
    {
        indices[i++] = ((y + 1) * width + (width - 1));
        indices[i++] = ((y + 1) * width);
    }   
}
}

结果：

4×2

指数 0, 5, 1, 6, 2, 7, 3, 8, 4, 9, 9, 5, 5, 10, 6, 11, 7, 12, 8, 13, 9, 14, 0, 0, 0 , 0, 0, 0, ...} 无符号整数 [42]

它做了 22 个正确的值，然后其余的都是零。

任何想法为什么？

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2 回答 2

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我认为你的循环需要看起来像这样（小心未经测试:)。基本上可以将其视为在四边形上循环并输出三角形对的索引。

for (int y = 0; y < height; y++)
{
    unsigned int base = y * width;
    unsigned int top = base + width;
    for (int x = 0; x < (width-1); x++)
    {
        indices[i++] = base + x;
        indices[i++] = top + x; 
        indices[i++] = top + x + 1; 

        indices[i++] = top + x + 1;
        indices[i++] = base + x + 1; 
        indices[i++] = base + x; 
    }
}
于 2014-08-09T15:26:11.890 回答
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我意识到顶点是从下到上创建的，并且索引被命令从上到下创建三角形。所以我改变了循环的顶点创建。

int index = 0;
for (int y = height; y >= 0; y--)
{

    for (int x = 0; x <= width; x++)
    {
        vertices[index] = ((float)x/4)-0.5;
        vertices[index +1] = ((float)y/4)-0.5;
        vertices[index + 2] = 0.0f;
        index += 3;
    }
}

它从左上角到右下角创建顶点。索引的循环保持不变：

int i = 0;
++width;
GLuint indices2[170] = { 0 };

for (int y = 0; y < height; y++)
{
    int base = y * width;

    for (int x = 0; x < width; x++)
    {
        indices[i++] = base + x;
        indices[i++] = base + width + x;
    }
    if (y < height - 1)
    {
        indices[i++] = ((y + 1) * width + (width - 1));
        indices[i++] = ((y + 1) * width);
    }
}
于 2014-08-15T08:49:21.377 回答