Skip to main content

Plane-Like rotating...

Alsalam alikom wa ra7mat allah wa barakatoh

Here is some explaination about how to rotate the camera just like the plane rotates...

We have Up Vector and a View Vector, to make the camera rotates right, we rotate the view vector about 0,1,0 vector with the angle we wish...

RotateView(-0.1f, 0, 1, 0);

RotateView will just calculate the new viewVector after multiplying it by the 3D Rotation matrix...

This is just regular,

Now how to make the the camera (the plane) rotates, we will simply rotate the upVector around the view vector but here will arise a problem that when we continue rotating right, the upVector will just miss the whole thing... mm try to imagine it.. we rotated it about a vector (view) then this view vector changed its direction, then we continue rotating it about the new view... blah blah.. just a total miss..

Actually, I don't know the professional way to solve it, but i got two good ideas (in my opinion), first one is whenever we rotate the view, we rotate the upVector about 0,1,0 with the same angle we rotated the view with... this will keep the upVector always perpendicular to the view vector and just looking rotated..
Second one is whenever we rotate the viewVector, we reset the upVector to 0,1,0 then rotate it with the total angle... instead of stepping each time 0.1 or whatever....

Both solutions r similar.. i'm attaching the code of the first one..


void CCamera::RotateView(float angle, float x, float y, float z)
{
CVector3 vNewView;
CVector3 vView = m_vView - m_vPosition;
float cosTheta = (float)cos(angle);
float sinTheta = (float)sin(angle);
vNewView.x = (cosTheta + (1 - cosTheta) * x * x) * vView.x;
vNewView.x += ((1 - cosTheta) * x * y - z * sinTheta) * vView.y;
vNewView.x += ((1 - cosTheta) * x * z + y * sinTheta) * vView.z;

vNewView.y = ((1 - cosTheta) * x * y + z * sinTheta) * vView.x;
vNewView.y += (cosTheta + (1 - cosTheta) * y * y) * vView.y;
vNewView.y += ((1 - cosTheta) * y * z - x * sinTheta) * vView.z;

vNewView.z = ((1 - cosTheta) * x * z - y * sinTheta) * vView.x;
vNewView.z += ((1 - cosTheta) * y * z + x * sinTheta) * vView.y;
vNewView.z += (cosTheta + (1 - cosTheta) * z * z) * vView.z;

m_vView = m_vPosition + vNewView;

// This part will rotate the upVector about 0,1,0 with the same rotation angle of the viewVector
RotateUp(angle, 0, 1, 0);
}
void CCamera::RotateUp(float angle, float x, float y, float z)
{
CVector3 vNewView;
CVector3 vUp = m_vUpVector;
float cosTheta = (float)cos(angle);
float sinTheta = (float)sin(angle);

vNewView.x = (cosTheta + (1 - cosTheta) * x * x) * vUp.x;
vNewView.x += ((1 - cosTheta) * x * y - z * sinTheta) * vUp.y;
vNewView.x += ((1 - cosTheta) * x * z + y * sinTheta) * vUp.z;

vNewView.y = ((1 - cosTheta) * x * y + z * sinTheta) * vUp.x;
vNewView.y += (cosTheta + (1 - cosTheta) * y * y) * vUp.y;
vNewView.y += ((1 - cosTheta) * y * z - x * sinTheta) * vUp.z;

vNewView.z = ((1 - cosTheta) * x * z - y * sinTheta) * vUp.x;
vNewView.z += ((1 - cosTheta) * y * z + x * sinTheta) * vUp.y;
vNewView.z += (cosTheta + (1 - cosTheta) * z * z) * vUp.z;

m_vUpVector = vNewView;
}

* Note : the code of multiplying with the matrix is not mine, i copied it (as it's) from GameTutorials

- Now, u can simply call (in ur VK_RIGHT) something like this

RotateView(-0.1f, 0, 1, 0);
CVector3 vAxis = m_vView - m_vPosition;
vAxis = Normalize(vAxis);
RotateUp(0.1f, vAxis.x, vAxis.y, vAxis.z);

This will give u the desidered effect, of course u can play with -0.1f and 0.1f values to make it looks better, or make it depend on ur straight-forward speed... but this is another story :)...

Hope u (me :D) enjoy it..

Alsalam alikom wa ra7mat allah wa barakatoh

Comments

Popular posts from this blog

Windows7 adds Math Input Panel

Alsalam alikom wa ra7mat Allah wa barakatoh… I was reading a windows team post about Input Panels improvements in Windows7 [ here ]. When at the end I saw a very interesting –intuitive if you wish- new thing… which is, as you guessed, the Math Input Panel… Yes, that crappy font is mine… I “drew” that by mouse as I don’t have a tablet pen/pc. You can then paste it directly into word and it’ll recognize it as an editable equation… During my tests, the output panel (the top part) hanged, but I liked that the drawing panel was still responsive and I could still write/erase… till the top one started to respond again… One other thing to know, after you click Insert (that button down there) it copies the equation in MathML [ Wikipedia link ] format.. which is a standard way of representing equations and hence any application that recognizes the format can insert it not as an image but as a nice editable equation… If you think it recognized something wrong, you can click “Sele...

Microsoft Web Platform Installer… coming near you

The Microsoft Web Platform Installer 2.0 (Web PI) is a free tool that makes it simple to download, install and keep up-to-date with the latest components of the Microsoft Web Platform, including Internet Information Services (IIS), SQL Server Express, .NET Framework and Visual Web Developer. In addition, install popular open source ASP.NET and PHP web apps with the Web PI. Here is the code snippet if you want to spread the word :) < a href ="http://go.microsoft.com/fwlink/?LinkId=146503" title=" Get the Microsoft Web Platform " > < img src ="http://www.microsoft.com/web/media/badge/get_microsoft_web_platform.png" alt ="Get the Microsoft Web Platform" border ="0" /> </ a >

Question Google Chrome Process Isolation Model..

Alsalam alikom wa ra7mat Allah wa barakatoh Google once published this comics book about Google chrome (their Open Source Web Browser) I've linked to one page that I'm concerning about for now... Page 4, Google Chrome Comics Book It explains that Chrome will have separate process per tab, away from the benefits/concerns about this... I was accidently checking chrome's task manager (Shift + Esc) and found something that -apparently- violates this rule... As you see, tab1 process has actually spanned 3 tabs... which is a similar behavior to what IE8 does... I'm not quite sure why this happens in Chrome... but it's just a question to ask... Thanks, Haytham