Camera Class

Shane Lillie · 2004-10-26T11:08:35

I've been trying to come up with a decent camera class for myself (I know there's a new article up on this, but I'm trying to make sure I really understand what's going on). This is what I have so far: Camera.h /* ==================== File: Camer.h Author: Shane Lillie Description: Camera module header. ==================== */ #if !defined __CAMERA_H__ #define __CAMERA_H__ #if _MSC_VER >= 1000 #pragma once #endif #include "EnVector.h" /* class Camera */ class Camera { public: Camera(); ~Camera(); public: // calls gluLookAt() // does contraints on the camera void look(); // moves the camera // in the looking direction void move(const EnVector3<GLdouble>& vector); // rotates the camera // (these are angles in degrees) void rotate(GLfloat yaw, GLfloat pitch); private: EnVector3<GLdouble> m_position; EnVector3<GLdouble> m_lookat; EnVector3<GLdouble> m_up; GLfloat m_yaw, m_pitch; private: Camera(const Camera& camera); Camera& operator=(const Camera& rhs); }; #endif Camera.cpp /* ==================== File: Camer.cc Author: Shane Lillie Description: Camera module source. ==================== */ #include <cassert> #include <cmath> #include <iostream> #include <GL/glut.h> #include "Camera.h" #define DEG_RAD(d) ((d) * 0.0174532925) // M_PI / 180.0 is about 0.0174532925 /* * Camera methods * */ Camera::Camera() : m_position(0.0, 0.0, 10.0), m_lookat(0.0, 0.0, -90.0), m_up(0.0, 1.0, 0.0), m_yaw(90.0), m_pitch(0.0f) { } Camera::~Camera() { } void Camera::look() { gluLookAt(m_position.x(), m_position.y(), m_position.z(), m_position.x() + m_lookat.x(), m_position.y() + m_lookat.y(), m_position.z() + m_lookat.z(), m_up.x(), m_up.y(), m_up.z()); #if 1 glBegin(GL_LINES); glVertex3f(m_position.x(), m_position.y(), m_position.z()); glVertex3f(m_position.x() + m_lookat.x(), m_position.y() + m_lookat.y(), m_position.z() + m_lookat.z()); glEnd(); #endif } void Camera::move(const EnVector3<GLdouble>& vector) { // rotate the vector into // the direction we're looking // only on the xz-plane EnVector3<GLdouble> nv(vector); nv[0] += std::cos(DEG_RAD(m_yaw)); // move the camera in the // direction we're looking m_position += nv; } void Camera::rotate(GLfloat yaw, GLfloat pitch) { m_yaw += yaw; m_pitch -= pitch; // constrain the yaw if(m_yaw <= -360.0 || m_yaw >= 360.0) m_yaw = 0.0; // constrain the pitch if(m_pitch > 60.0) m_pitch = 60.0; else if(m_pitch < -60.0) m_pitch = -60.0; std::cout << "yaw: " << m_yaw << ", pitch: " << m_pitch << std::endl; // set the new lookat vector // radius = 100 m_lookat = EnVector3<GLdouble>(std::cos(DEG_RAD(m_yaw)), std::sin(DEG_RAD(m_pitch)), -std::sin(DEG_RAD(m_yaw))); std::cout << m_lookat.to_string() << std::endl; /* // set the new up vector // (position - lookat) x vector EnVector3<GLdouble> vector = m_position - m_lookat; if(!m_yaw) m_up = vector.cross(EnVector3<GLdouble>(-1.0, 0.0, 0.0)); // looking down the z-axis else if(m_yaw > 0.0f) m_up = vector.cross(EnVector3<GLdouble>(0.0, 0.0, -1.0)); // positive rotation else m_up = vector.cross(EnVector3<GLdouble>(0.0, 0.0, 1.0)); // negative rotation std::cout << m_up.to_string() << std::endl;*/ } Assuming all of my vector operations are done correctly, I'm wondering why my rotations don't work quite right. For example, if I rotate towads the +x-axis and then move down the rotated z-axis, then back on the z-axis, then forward and so on, it moves me down the x-axis. I'm sure it's something being inconsistant between my rotation and movement calculations, it's just not clear to me what it is. I appreciate any advice or suggestions. I'm not so good with the math here so it's been a very slow process getting what I have. I feel close to the correct solution, it's just enough out of my reach that I don't see what I'm doing wrong. EDIT - Also, the line I'm trying to draw from my position to where I'm looking (so I can see where I'm looking) doesn't show up at all. I have a polygon I'm rendering in front of me that I'm using a reference, but I'd really like to see that line if I can get it. [Edited by - Chozo on October 18, 2004 4:58:13 PM]

Graphics and GPU Programming Programming

Started by Chozo October 17, 2004 02:45 PM

52 comments, last by Chozo 19 years, 6 months ago

Chozo

176

Author

October 22, 2004 12:58 PM

Test came out okay. This:

EnVector3<float> vec(0.0f, 0.0f, 1.0f);std::cout << "Test1 before: " << vec.to_string() << std::endl;EnQuaternion<float> quat(std::cos(M_PI_2 / 2.0f), std::sin(M_PI_2 / 2.0f), 0.0f, 0.0f);std::cout << "Test1 after: " << quat.rotate(vec).to_string() << std::endl;vec = EnVector3<float>(1.0f, 0.0f, 0.0f);std::cout << "Test2 before: " << vec.to_string() << std::endl;quat = EnQuaternion<float>(std::cos(M_PI_2 / 2.0f), 0.0f, 0.0f, std::sin(M_PI_2 / 2.0f));std::cout << "Test2 after: " << quat.rotate(vec).to_string() << std::endl;vec = EnVector3<float>(0.0f, 1.0f, 0.0f);std::cout << "Test3 before: " << vec.to_string() << std::endl;quat = EnQuaternion<float>(std::cos(M_PI_2 / 2.0f), 0.0f, 0.0f, std::sin(M_PI_2 / 2.0f));std::cout << "Test3 after: " << quat.rotate(vec).to_string() << std::endl;

Gives this:

Test1 before: (0, 0, 1)Test1 after: (0, -1, 0)Test2 before: (1, 0, 0)Test2 after: (0, 1, 0)Test3 before: (0, 1, 0)Test3 after: (-1, 0, 0)

Those look like the proper rotations when I work it out in my head. Just furthering my confusion now.

Chozo

176

Author

October 23, 2004 02:37 PM

No ideas?

Dmytry

1,151

October 23, 2004 03:07 PM

Quote:Original post by Dmytry
BTW.
Quote:
EnQuaternion<float> q(std::cos(M_PI_2 / 2.0f), 1.0f, 0.0f, 0.0f);
EnVector3<float> v(1.0f, 0.0f, 0.0f);

m_log.vlogln(LogOutputNormal, "Before rotation: %s", v.to_string().c_str());
v = q.rotate(v);
m_log.vlogln(LogOutputNormal, "After rotation: %s", v.to_string().c_str());

- your quaternion is not unit-length.
Therefore, rotated vector is not unit length. So your quaternion class *might* even be correct :)
you can test your quaternion against other quaternion class such as my.

- Simply said, your first test is incorrect.
and result

Quote:
I get this output:
Before rotation: (1, 0, 0)
After rotation: (1.5, 0, 0)

probably may be ignored.

Chozo

176

Author

October 24, 2004 01:32 PM

But my second set of tests came out okay. Which, to the best of my knowledge says my quat class is rotating vectors okay. Is that correct? I'm at a loss for what I need to fix because everything seems like it should be working.

Dmytry

1,151

October 24, 2004 02:03 PM

If you want to to completely make sure(not only for special cases), you can compare your results for arbitrary quaternion and arbitrary vector to my results:

Vec3d v(1.2345,2.3456,4.67342);	Quaterniond q(0.592031,0.43251,-0.75362,0.12415);// constructor parameters: (scalar,x,y,z)	Normalize(q);	Quaterniond q2(-0.23456634,0.942123,-0.42121,0.374812);		Normalize(q2);	cout<<"q="<<q<<endl;	cout<<"v="<<v<<endl;	cout<<"q*v="<<QuaternionToMatrix(q)*v<<endl;	cout<<"q2="<<q2<<endl;	cout<<"q*q2="<<q*q2<<endl;results:q=quaternion:[0.559187,      0.408515,       -0.711811,      0.117262]v=vector:[1.2345,        2.3456, 4.67342]q*v=vector:[-4.9948,       -1.97318,       0.158859]q2=quaternion:[-0.208925,     0.839137,       -0.375166,      0.33384]q*q2=quaternion:[-0.765823,     0.190247,       -0.0990524,     0.606226]

If your code outputs same results, it must be right, if it outputs different results it might be right if my quaternion rotation is accidently non-standard(mirrored) (really hard to notice such problem) . Your rotation surely must be standard...

Dmytry

1,151

October 24, 2004 02:11 PM

BTW, there's probably a language confusion. By "your first test is incorrect." i meant that "test is incorrect" , not "quaternion rotation is incorrect".

[Edited by - Dmytry on October 24, 2004 3:11:57 PM]

Chozo

176

Author

October 24, 2004 02:20 PM

Is it important to note that if I move beind an object and then turn around, the controls end up reversed?

Dmytry

1,151

October 24, 2004 03:18 PM

Quote:Original post by Chozo
Is it important to note that if I move beind an object and then turn around, the controls end up reversed?

if there's bug, you need to test your quaternion, then test something else, till you find the bug. Test arbitrary quaternions i gave - if it works, your quaternion*vector and quaternion*quaternion code is correct.

Chozo

176

Author

October 24, 2004 05:07 PM

Could this be part of the problem (these are from my quat class)?

    // vector multiplication    template <class V>    EnQuaternion<T> operator*(const EnVector3<V>& rhs)    {        return *this * EnQuaternion<T>(0, rhs);    }    // vector multiplication    // and assignment    template <class V>    const EnQuaternion<T>& operator*=(const EnVector3<V>& rhs)    {        *this = *this * EnQuaternion<T>(0, rhs);        return *this;    }

My q * v returns a quaternion, not a vector (* as in multiply, not rotate). Everything I read said that when you multiply a quat and a vector, it's the same as multiplying the quat by a new quat with a scalar of 0 and the vector as the vector multiplying by. ie, quat(0, vector).

All the other tests you gave me came out as expected.

Dmytry

1,151

October 24, 2004 05:24 PM

Quote:Original post by Chozo
Could this be part of the problem (these are from my quat class)?

*** Source Snippet Removed ***

My q * v returns a quaternion, not a vector (* as in multiply, not rotate). Everything I read said that when you multiply a quat and a vector, it's the same as multiplying the quat by a new quat with a scalar of 0 and the vector as the vector multiplying by. ie, quat(0, vector).

All the other tests you gave me came out as expected.

I'd not define that multiplication at all to be safe. I don't sure it's mathematically defined thing. You shouldn't be using it too often.

It's one of reasons why to rotate vector using quaternion i use
QuaternionToMatrix(q)*v;

I don't have quaternion*vector operator, i just accidently wrote q*v in that test for cout , it's may be somewhat confusing.

Also i see std::memmove in your code. Don't use it, just use = .

Camera Class

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