我有......独特的问题。我正在制作一个游戏，我将动态绘制点（代表城市）与它们之间的飞行路径。然后，用户将选择这些城市并执行进一步的操作。
此外，地球必须能够围绕一个轴旋转，因此用户可以轻松地查看所有城市。
我找到了一种在球体上绘制点和路径的方法。这些点是微小的球体，路径是我生成的贝塞尔曲线。我把它们包含在一个glpushmatrix（）和glpopmatrix（）中，并在开始时调用glrotate（），以便所有事物（地球，路径和顶点）一致旋转
我面临的唯一问题是弄清楚用户点击了哪个顶点。 glrotate修改模型矩阵，所以我必须在每次旋转时计算顶点的新位置吗？我正在使用glunproject来确定用户点击的位置。 或者，有没有其他方法可以解决这个问题？
这是我的代码： -
float venusRotate;
vector<vector3f>cityVertices;
//bezier curve
GLfloat bezierCurve(float t, GLfloat P0,
GLfloat P1, GLfloat P2) {
// Cubic bezier Curve
GLfloat point = pow(t,2)*P0 + 2*P1*t*(1-t) + P2*pow(1-t, 2);
return point;
}
vector3f randomSpherePoint()
{
float u = static_cast <float> (rand()) / static_cast <float> (RAND_MAX);
float v = static_cast <float> (rand()) / static_cast <float> (RAND_MAX);
float theta = 2 * M_PI * u;
float phi = acos(2*v-1);
float x=(10*sin(phi)*cos(theta));
float y=(10 * sin(phi) * sin(theta));
float z=10*cos(phi);
return vector3f(x, y, z);
}
void drawRandomSpherePoints()
{
for (int i=0; i<400; i++)
{
glPushMatrix();
vector3f point=cityVertices.at(i);
glTranslatef(point.x, point.y, point.z);
glutSolidSphere(0.25, 10, 10);
glPopMatrix();
}
}
vector3f GetOGLPos(int x, int y)
{
GLint viewport[4];
GLdouble modelview[16];
GLdouble projection[16];
GLfloat winX, winY, winZ;
GLdouble posX, posY, posZ;
glGetDoublev( GL_MODELVIEW_MATRIX, modelview );
glGetDoublev( GL_PROJECTION_MATRIX, projection );
glGetIntegerv( GL_VIEWPORT, viewport );
winX = (float)x;
winY = (float)viewport[3] - (float)y;
glReadPixels( x, int(winY), 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ );
gluUnProject( winX, winY, winZ, modelview, projection, viewport, &posX, &posY, &posZ);
return vector3f(posX, posY, posZ);
}
void mouseClick(int button,int state,int x, int y)
{
vector3f Coord=GetOGLPos(x, y);
cout<<Coord.x<<" "<<Coord.y<<" "<<Coord.z<<endl;
// for (int i=0;i<cityVertices.size();i++)
// {
// if (Coord.x-cityVertices.at(i).x<CLICK_ACCURACY && Coord.z-cityVertices.at(i).z<CLICK_ACCURACY && Coord.z-cityVertices.at(i).z<CLICK_ACCURACY ) {
// }
// }
}
void preProcessEvents()
{
CURRENT_TIME=(float)glutGet(GLUT_ELAPSED_TIME);
DELTA_TIME=CURRENT_TIME-LAST_TIME;
LAST_TIME=CURRENT_TIME;
mouse::update();
//mouse processing
Camera::rotationAngles.y+=(float)mouse::deltaX*MOUSE_SENSITIVITY;
Camera::rotationAngles.x-=(float)mouse::deltaY*MOUSE_SENSITIVITY;
if (Camera::rotationAngles.x>MAX_TILT)
{
Camera::rotationAngles.x=MAX_TILT;
}
else if (Camera::rotationAngles.x<-1*MAX_TILT)
{
Camera::rotationAngles.x=-1*MAX_TILT;
}
if (keyBoard::key['w'])
{
Camera::position.z-=WALKING_SPEED*DELTA_TIME*Math::sind(Camera::rotationAngles.y);
Camera::position.x-=WALKING_SPEED*DELTA_TIME*Math::cosd(Camera::rotationAngles.y);
}
else if (keyBoard::key['s'])
{
Camera::position.z+=WALKING_SPEED*DELTA_TIME*Math::sind(Camera::rotationAngles.y);
Camera::position.x+=WALKING_SPEED*DELTA_TIME*Math::cosd(Camera::rotationAngles.y);
}
else if (keyBoard::key['a'])
{
Camera::rotationAngles.y-=WALKING_SPEED*DELTA_TIME*3;
}
else if (keyBoard::key['d'])
{
Camera::rotationAngles.y+=WALKING_SPEED*DELTA_TIME*3;
}
else if (keyBoard::key['f'])
{
venusRotate++;
}
else if (keyBoard::key[' '])
{
glutDestroyWindow(subWindow);
}
}
void reshape(int w, int h)
{
float aspectRatio;
if (h==0)
{
h=1;
}
aspectRatio=float(w)/float(h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glViewport(0, 0, w ,h);
gluPerspective(45, aspectRatio, 0.01, 100000000);
glMatrixMode(GL_MODELVIEW);
}
void display()
{
preProcessEvents();
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
gluLookAt(Camera::position.x, Camera::position.y, Camera::position.z,
Camera::position.x+Math::sind(Camera::rotationAngles.x)*Math::cosd(Camera::rotationAngles.y),
Camera::position.y+Math::cosd(Camera::rotationAngles.x),
Camera::position.z+Math::sind(Camera::rotationAngles.x)*Math::sind(Camera::rotationAngles.y),
0.0, 1.0, 0.0);
glBegin(GL_TRIANGLES);
glColor3f(1, 0, 0);
glVertex3f(-1, 0,-3);
glColor3f(0, 1, 0);
glVertex3f(0.0f, 2.0f,-3);
glColor3f(0, 0, 1);
glVertex3f(1.0f, 0.0f,-3);
glEnd();
glBindTexture(GL_TEXTURE_2D, tex->textureID);
glBegin(GL_QUADS);
glColor3f(1, 1, 1);
glTexCoord2f(100, 100);
glVertex3f(100,0,100);
glTexCoord2f(-100, 100);
glVertex3f(-100,0,100);
glTexCoord2f(-100,-100);
glVertex3f(-100,0,-100);
glTexCoord2f(100,-100);
glVertex3f(100,0,-100);
glEnd();
glBindTexture(GL_TEXTURE_2D, 0);
glPushMatrix();
object1.draw();
glPopMatrix();
//globe
glTranslatef(-10.0, 10.0, 0.0);
glBindTexture(GL_TEXTURE_2D, tex2->textureID);
gluQuadricTexture(quad,1);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glRotatef(-90, 1.0f, 0.0f, 0.0f);
glRotatef(venusRotate, 0.0, 0.0, 1.0);
drawRandomSpherePoints();
for (int i=0; i<cityVertices.size()-1; i++)
{
vector3f start=cityVertices.at(i);
vector3f end=cityVertices.at(i+1);
vector3f perpBisectorDirection=vector3f((start.x+end.x)/2,(start.y+end.y)/2,(start.z+end.z)/2);
vector3f tan1(perpBisectorDirection.x/10*15,perpBisectorDirection.y/10*15,perpBisectorDirection.z/10*15);
glColor3f(1.0, 0.0, 0.0);
glLineWidth(12.0);
glBegin(GL_LINE_STRIP);
int t = 30;
for (int i = 0; i <= t; i++) {
float pos = (float) i / (float) t;
GLfloat x = bezierCurve( pos,start.x, tan1.x, end.x);
GLfloat y = bezierCurve( pos,start.y, tan1.y, end.y);
// In our case, the z should always be empty
GLfloat z = bezierCurve(pos,start.z, tan1.z, end.z);
vector3f result(x, y, z);
glVertex3f(x, y, z);
}
glEnd();
}
gluSphere(quad,10,20,20);
glPopMatrix();
glBindTexture(GL_TEXTURE_2D, 0);
glutSwapBuffers();
}
答案 0 :(得分：1)
Opengl有一个选择模式
glRenderMode（GL_SELECT）;