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我正在尝试使用 GLSL 渲染带有 Phong 着色的三角形网格，这是我分配法线的方法。

void renderWireframe(Mesh *mesh) 
{
    glDepthMask(GL_TRUE);
    glBegin(GL_TRIANGLES);
    for(int i=0; i<mesh->nt; i++) { //nv is the mesh's number of triangles

    int i0 = mesh->triangles[i].vInds[0];
    int i1 = mesh->triangles[i].vInds[1];
    int i2 = mesh->triangles[i].vInds[2];

    //Calculate normals for each vertex
    Vector fv0 = getvertexnormal(mesh, i0);
    Vector fv1 = getvertexnormal(mesh, i1);
    Vector fv2 = getvertexnormal(mesh, i2);

    glNormal3dv((double *)&fv0);
    glVertex3dv((double *)&mesh->vertices[i0]);
    glNormal3dv((double *)&fv1);
    glVertex3dv((double *)&mesh->vertices[i1]);
    glNormal3dv((double *)&fv2);
    glVertex3dv((double *)&mesh->vertices[i2]);
    }
glEnd();
}

getvertexnormal 代码如下所示：

Vector getvertexnormal(Mesh *mesh, int vertex){
    int i = mesh->nt; //nt is the mesh's number of triangles
    int *adjface;
    adjface = new int[i]; //array to store adjacent faces

    //Store each triangle which has an intersection with the vertex'th vertex
    int nadjface = 0; 
    Triangle *t = mesh->triangles;
    for (int ix = 0; ix < mesh->nt; ix++){
        if(t[ix].vInds[0] == vertex){
            adjface[nadjface++] = ix;
        }
        else
            if (t[ix].vInds[1] == vertex)
                adjface[nadjface++] = ix;
            else
                if (t[ix].vInds[2] == vertex)
                    adjface[nadjface++] = ix;
    }

    // Average all adjacent triangles normals to get the vertex normal
    Vector norm = {0.0, 0.0, 0.0};
    for (int jx = 0; jx < nadjface; jx++){
        int ixFace = adjface[jx];
        norm.x += mesh->triangles[ixFace].vInds[0];
        norm.y += mesh->triangles[ixFace].vInds[1];
        norm.z += mesh->triangles[ixFace].vInds[2];
    }
    norm.x /= nadjface;
    norm.y /= nadjface;
    norm.z /= nadjface;
    return Normalize(norm);
}

每次我运行它时，它看起来像是开始渲染，然后一秒钟后它崩溃并给我一个异常：

“ glutglsl.exe 中 0x7562B727 处未处理的异常：Microsoft C++ 异常：内存位置 0x0028F1C8 处的 std::bad_alloc。”

如果我注释掉 getvertexnomral() 部分而不是

glNormal3dv((double *)&fv0);
glVertex3dv((double *)&mesh->vertices[i0]);
glNormal3dv((double *)&fv1);
glVertex3dv((double *)&mesh->vertices[i1]);
glNormal3dv((double *)&fv2);
glVertex3dv((double *)&mesh->vertices[i2]);

我写的

glNormal3dv((double *)&Normalize(mesh->vertices[i0]));
glVertex3dv((double *)&mesh->vertices[i2]);
glNormal3dv((double *)&Normalize(mesh->vertices[i1]));
glVertex3dv((double *)&mesh->vertices[i1]);
glNormal3dv((double *)&Normalize(mesh->vertices[i2]));
glVertex3dv((double *)&mesh->vertices[i2]);

但它看起来不正确（http://imgur.com/lxSUMAq）

所以我认为getvertexnormal() 有问题。

顺便说一句，我在这方面完全是新手。我的片段着色器（GLSL）中有我所有的 phong 计算。要在大三角形网格上实现 phong 着色，这是正确的方法吗？

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1 回答 1

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你的问题是内存泄漏。

你正在分配内存

adjface = new int[i];

但你永远不会删除它。从返回的值new存储在局部变量中，永远不会复制到任何地方，也不会从函数返回。所以你所拥有的是内存泄漏，这会导致内存耗尽和分配错误 - 所以newthrows std::bad_alloc。

这是 C++。不要使用数组；改为使用std::vector。或者delete[]它。

但我认为你在这里并不需要一个数组：

Vector getvertexnormal(Mesh *mesh, int vertex) {
    int nadjface = 0; 
    Triangle *t = mesh->triangles;
    Triangle *last = t + (mesh->nt - 1);
    Vector norm = {0.0, 0.0, 0.0};
    for (; t <= last; t++) {
        for (int i = 0; i < 3; i++) {
            if (t->vInds[i] == vertex) {
                nadjface++;
                norm.x += t->vInds[0];
                norm.y += t->vInds[1];
                norm.z += t->vInds[2];
                break;
            }
        }
    }
    return Normalize(norm / nadjface);
}

如果我没记错的话，你可以简单地做

norm += t->vInds;

或类似的东西。它可以让你的代码更短、更易读，甚至可能更快。

于 2013-06-27T13:34:49.373 回答