Hi,
I have a 3D world and want to move around in it. If the user presses the left or right arrow keys they rotate left or right by 4 degrees.
If they press up they start moving forward. If they press it again their speed increases (and opposite for back arrow).
I wrote the following in C++ and OpenGL. The code works perfectly as long as you never rotate while moving. If you stop and rotate and then start moving, the camera "moves" correctly down the line of sight. My knowledge of linear algebra is minimal and I am sure that is where my problem is.
Also, when the program first loads the user is looking in the +Y direction.
Here is my function that draws the scene every frame:
void display(void)
{
//Calculate current altitude
altitude = (altitude + -1*oz);
glutSetWindow(window3D);
glTranslatef(ox,oy,oz); //Translate to a new position (if updated)
//Keep track of current acft position
posx = posx + ox;
posy = posy + oy;
posz = posz + oz;
glClearColor(0, 0, 1, 0.0); //Set Sky color
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//Draw ground and orientate correctly
glPushAttrib(GL_ALL_ATTRIB_BITS);
glPushMatrix();
glRotatef(90,1,0,0);
glScalef(worldx+10,1,worldy+10);
glBegin(GL_QUADS);
glColor3f(wc1, wc2, wc3); //Set color of ground
glVertex3f( 0.5f,-0.5f, 0.5f);
glVertex3f(-0.5f,-0.5f, 0.5f);
glVertex3f(-0.5f,-0.5f,-0.5f);
glVertex3f( 0.5f,-0.5f,-0.5f);
glEnd();
glPopAttrib();
glPopMatrix();
drawObjects(); //Call function to draw world
glutSwapBuffers();
}
Here is my code when the user presses a key:
//Right = posive
void rotateMe(int direction)
{
glutSetWindow(window3D);
arrowAngle = (arrowAngle + (direction*5));
glTranslatef(-posx,-posy,-posz);
glRotatef(direction*5,0,0,1);
glTranslatef(posx,posy,posz);
}//function
//Function that moves user
//Direction specifies forward or backwards
//Back = negative
//Forward = posive
void moveMe(int direction)
{
glutSetWindow(window3D);
rad = arrowAngle * (3.14/180); //Convert to radians
ox = (ox + direction*sin(rad));
oy = (oy + direction*cos(rad));
}//function
//Function to process special keys
void specialKeyboard(int key, int kx, int ky)
{
/* LEGEND
Page Up - Increase altitude
Page Down - Decrease altitude
Left Arrow - Turn Left
Right Arrow - Turn Right
Forward Arrow - Move forward
Back Arrow - Move backward
*/
switch (key)
{
case GLUT_KEY_PAGE_DOWN :
//check to ensure rate of climb is not too steep
if ((oz < maxclimb))
{
counter--;
oz = oz + 0.3;
}
break;
case GLUT_KEY_PAGE_UP :
//check to ensure rate of climb is not too steep
if ((oz > -1*maxclimb))
{
counter++;
oz = oz - 0.3;
}
break;
case GLUT_KEY_LEFT :
rotateMe(-1);
break;
case GLUT_KEY_RIGHT :
rotateMe(+1);
break;
case GLUT_KEY_UP :
moveMe(-1);
break;
case GLUT_KEY_DOWN :
moveMe(+1);
break;
} //Switch
if (counter == 0)
oz = 0;
} //Function
