我已经实现了截锥体剔除并正在检查边界框与截锥体平面的交集。我添加了暂停视锥体更新的功能,这让我可以查看视锥体剔除是否正常工作。当我暂停后转身时,我身后以及左侧和右侧没有任何渲染,它们逐渐变细,正如您所期望的那样。在剪辑距离(远平面)之外,它们仍然呈现,我不确定这是否是我的平截头体更新或边界框检查代码的问题,或者我使用了错误的矩阵还是什么。当我将投影矩阵中的距离设置为 3000.0f 时,它仍然表示边界框远远超过了它仍在平截头体中,但事实并非如此。
这里是我创建模型 View 矩阵的地方:
projectionMatrix = glm::perspective(newFOV, 4.0f / 3.0f, 0.1f, 3000.0f);
viewMatrix = glm::mat4(1.0);
viewMatrix = glm::scale(viewMatrix, glm::vec3(1.0, 1.0, -1.0));
viewMatrix = glm::rotate(viewMatrix, anglePitch, glm::vec3(1.0, 0.0, 0.0));
viewMatrix = glm::rotate(viewMatrix, angleYaw, glm::vec3(0.0, 1.0, 0.0));
viewMatrix = glm::translate(viewMatrix, glm::vec3(-x, -y, -z));
modelViewProjectiomMatrix = projectionMatrix * viewMatrix;
我在 Z 方向按 -1 缩放它的原因是因为关卡设计为使用 DirectX 渲染,所以我反转 Z 方向。
这是我更新截锥体的地方:
void CFrustum::calculateFrustum()
{
glm::mat4 mat = camera.getModelViewProjectionMatrix();
// Calculate the LEFT side
m_Frustum[LEFT][A] = (mat[0][3]) + (mat[0][0]);
m_Frustum[LEFT][B] = (mat[1][3]) + (mat[1][0]);
m_Frustum[LEFT][C] = (mat[2][3]) + (mat[2][0]);
m_Frustum[LEFT][D] = (mat[3][3]) + (mat[3][0]);
// Calculate the RIGHT side
m_Frustum[RIGHT][A] = (mat[0][3]) - (mat[0][0]);
m_Frustum[RIGHT][B] = (mat[1][3]) - (mat[1][0]);
m_Frustum[RIGHT][C] = (mat[2][3]) - (mat[2][0]);
m_Frustum[RIGHT][D] = (mat[3][3]) - (mat[3][0]);
// Calculate the TOP side
m_Frustum[TOP][A] = (mat[0][3]) - (mat[0][1]);
m_Frustum[TOP][B] = (mat[1][3]) - (mat[1][1]);
m_Frustum[TOP][C] = (mat[2][3]) - (mat[2][1]);
m_Frustum[TOP][D] = (mat[3][3]) - (mat[3][1]);
// Calculate the BOTTOM side
m_Frustum[BOTTOM][A] = (mat[0][3]) + (mat[0][1]);
m_Frustum[BOTTOM][B] = (mat[1][3]) + (mat[1][1]);
m_Frustum[BOTTOM][C] = (mat[2][3]) + (mat[2][1]);
m_Frustum[BOTTOM][D] = (mat[3][3]) + (mat[3][1]);
// Calculate the FRONT side
m_Frustum[FRONT][A] = (mat[0][3]) + (mat[0][2]);
m_Frustum[FRONT][B] = (mat[1][3]) + (mat[1][2]);
m_Frustum[FRONT][C] = (mat[2][3]) + (mat[2][2]);
m_Frustum[FRONT][D] = (mat[3][3]) + (mat[3][2]);
// Calculate the BACK side
m_Frustum[BACK][A] = (mat[0][3]) - (mat[0][2]);
m_Frustum[BACK][B] = (mat[1][3]) - (mat[1][2]);
m_Frustum[BACK][C] = (mat[2][3]) - (mat[2][2]);
m_Frustum[BACK][D] = (mat[3][3]) - (mat[3][2]);
// Normalize all the sides
NormalizePlane(m_Frustum, LEFT);
NormalizePlane(m_Frustum, RIGHT);
NormalizePlane(m_Frustum, TOP);
NormalizePlane(m_Frustum, BOTTOM);
NormalizePlane(m_Frustum, FRONT);
NormalizePlane(m_Frustum, BACK);
}
最后,我检查边界框的地方:
bool CFrustum::BoxInFrustum( float x, float y, float z, float x2, float y2, float z2)
{
// Go through all of the corners of the box and check then again each plane
// in the frustum. If all of them are behind one of the planes, then it most
// like is not in the frustum.
for(int i = 0; i < 6; i++ )
{
if(m_Frustum[i][A] * x + m_Frustum[i][B] * y + m_Frustum[i][C] * z + m_Frustum[i][D] > 0) continue;
if(m_Frustum[i][A] * x2 + m_Frustum[i][B] * y + m_Frustum[i][C] * z + m_Frustum[i][D] > 0) continue;
if(m_Frustum[i][A] * x + m_Frustum[i][B] * y2 + m_Frustum[i][C] * z + m_Frustum[i][D] > 0) continue;
if(m_Frustum[i][A] * x2 + m_Frustum[i][B] * y2 + m_Frustum[i][C] * z + m_Frustum[i][D] > 0) continue;
if(m_Frustum[i][A] * x + m_Frustum[i][B] * y + m_Frustum[i][C] * z2 + m_Frustum[i][D] > 0) continue;
if(m_Frustum[i][A] * x2 + m_Frustum[i][B] * y + m_Frustum[i][C] * z2 + m_Frustum[i][D] > 0) continue;
if(m_Frustum[i][A] * x + m_Frustum[i][B] * y2 + m_Frustum[i][C] * z2 + m_Frustum[i][D] > 0) continue;
if(m_Frustum[i][A] * x2 + m_Frustum[i][B] * y2 + m_Frustum[i][C] * z2 + m_Frustum[i][D] > 0) continue;
// If we get here, it isn't in the frustum
return false;
}
// Return a true for the box being inside of the frustum
return true;
}
最佳答案
我注意到了一些事情,特别是关于如何设置投影矩阵。对于初学者,gluProject 不会返回值,除非您使用某种包装器或奇怪的 api。 gluLookAt 的使用频率更高。
接下来,假设缩放、旋转和平移函数旨在更改模型 View 矩阵,您需要颠倒它们的顺序。 OpenGL 实际上并不移动对象;相反,它有效地移动原点,并使用 <0,0,0> 的新定义渲染每个对象。因此,您“移动”到要渲染的位置,然后根据需要旋转轴,然后拉伸(stretch)网格。
关于裁剪问题,大家可能要给glClipPlane()好好看看。如果其他一切大部分都有效,但似乎存在一些舍入误差,请尝试将 perspective(,,,) 函数中的近裁剪平面从 0.1 更改为 1.0(较小的值往往会弄乱 z -缓冲区)。
我看到很多不熟悉的语法,所以我认为您使用了某种包装器;但这里有一些 (Qt) 代码片段来 self 自己使用的 GL 项目。可能有帮助,不知道:
//This gets called during resize, as well as once during initialization
void GLWidget::resizeGL(int width, int height) {
int side = qMin(width, height);
padX = (width-side)/2.0;
padY = (height-side)/2.0;
glViewport(padX, padY, side, side);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60.0, 1.0, 1.0, 2400.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
//This fragment gets called at the top of every paint event:
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glLightfv(GL_LIGHT0, GL_POSITION, FV0001);
camMain.stepVars();
gluLookAt(camMain.Pos[0],camMain.Pos[1],camMain.Pos[2],
camMain.Aim[0],camMain.Aim[1],camMain.Aim[2],
0.0,1.0,0.0);
glPolygonMode(GL_FRONT_AND_BACK, drawMode);
//And this fragment represents a typical draw event
void GLWidget::drawFleet(tFleet* tIn) {
if (tIn->firstShip != 0){
glPushMatrix();
glTranslatef(tIn->Pos[0], tIn->Pos[1], tIn->Pos[2]);
glRotatef(tIn->Yaw, 0.0, 1.0, 0.0);
glRotatef(tIn->Pitch,0,0,1);
drawShip(tIn->firstShip);
glPopMatrix();
}
}
我假设您是 GL 的新手,所以如果我表现得有点迂腐,我深表歉意。
关于c++ - OpenGL - 平截头体不剔除远平面之外的多边形,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12167637/