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Obi-Dan

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About Obi-Dan

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  1. Matrix Yaw and Pitch

    I'm trying to create a first person style camera in OpenGL as part of my coursework.  This question is more about matricies and vectors so I thought the Math section would be best. The camera has a 4x4 matrix containing position, rotation etc. also it has a look-at and right vector. (I think I need an up vector too)   Currently the camera is able to move forwards in the direction it is facing or strafe from side to side:   void moveForward(float distance) { m_lookatVec.x = -sin(m_rotation.y); m_lookatVec.y = sin(m_rotation.x); m_lookatVec.z = cos(m_rotation.y); m_lookatVec.normalise(); m_position += m_lookatVec * distance; }   This works well when moving down the z axis but the up/down direction seems to flip when travelling up the z axis i.e. when facing upwards the camera moves down on the y axis or up on the y axis when facing downwards.   void moveRight(float distance) { m_rightVec.x = cos(m_rotation.y); m_rightVec.y = sin(m_rotation.x); m_rightVec.z = sin(m_rotation.y); m_rightVec.normalise(); m_position += m_rightVec * distance; }   Not sure if this method is correct, I sort of guessed it but it seems to work!   The other issue is with changing the direction of the camera. Rotating around the y axis is easy enough but I would like to be able to change the pitch too. At the moment the Y axis or Yaw is changed like so: void changeYaw (float degrees) { float rads = MathHelp::degreesToRadians(degrees); m_rotation.y += rads; }     The rotation vector is later added to a transform matrix with the translation and scale vectors and applied to the camera before rendering. void Camera::Update() { GUMatrix4 transform, translation, rotation, scale; GUVector3 rot = getRotation(); // Create matricies translation = GUMatrix4::translationMatrix(getX(), getY(), getZ()); rotation = GUMatrix4::rotationMatrix(rot.x, rot.y, rot.z); scale = GUMatrix4::scaleMatrix(1.0f, 1.0f, 1.0f); glMatrixMode(GL_PROJECTION); transform = getProjMat() * scale * rotation * translation; glLoadMatrixf((GLfloat*) &transform); }     I now need a changePitch method, changeRoll isn't really necessary right now. I'm also guessing the changeYaw method should change to use the up, look and right vectors but I'm not entirely sure how to use them.   Any help would be awesome! Thanks, Dan.    
  2. Brilliant! Thanks, that works perfectly for moving forward. What about the change pitch method?   All I need now is to be able to rotate, currently the camera rotates on the Y axis only which lets me move around but not up or down.
  3. I'm trying to create a first person style camera. So far I have moving along the x and y axes sorted and now need to work on changing the pitch of the camera. E.g. To move forward 2.5f units:   mainCamera->moveForward(2.5f); Camera is derived from MovableObject: void MovableObject::moveForward(float distance) { m_position.z += cos(m_rotation.y) * distance; m_position.x -= sin(m_rotation.y) * distance; }     m_position - position vector m_rotation - rotation vector (in radians)   The camera update method sorts out the matrix stuff...   void Camera::Update() { GUMatrix4 finalMat, translation, rotation, scale; GUVector3 rot = getRotation(); // Create matricies translation = GUMatrix4::translationMatrix(getX(), getY(), getZ()); rotation = GUMatrix4::rotationMatrix(rot.x, rot.y, rot.z); glMatrixMode(GL_PROJECTION); finalMat = getProjMat() * rotation * translation; glLoadMatrixf((GLfloat*) &finalMat); }   translation - the 4x4 translation matrix. rotation- the 4x4 rotation matrix.   The code above works beautifully for moving forwards on the x and z axes. At the moment the camera is rotated about the Y axis using the mouses horizontal movement.    void mouseMove(int x, int y) { if (mDown) { int dx = x - mouse_x; int dy = y - mouse_y; // rotate camera if (mainCamera) { mainCamera->setYaw(mainCamera->getYaw() + (float)-dx); } mouse_x = x; mouse_y = y; } }   I now want the camera to rotate about the x and z axes using the mouses vertical position. The camera then needs to move forwards with the Y axis included.   So far for changing the cameras pitch I have: void MovableObject::changePitch(float degrees) { // Convert change to radians float rads = MathHelp::degreesToRadians(degrees); // X rotate more when looking down Z axis m_rotation.x += cos(m_rotation.y) * rads; }       Hopefully this is making sense to somebody.    Thanks in advance! Dan.    
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