Sign in to follow this  

World, View, and Projection Matrices

This topic is 2035 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I have quite the trouble with the world, view, and projection matrices. I understand how the world matrix works, but I don't know how to implement it can you give an example? also for the perspective projection I use the following method:
[source lang="csharp"] public static Matrix3D ProjectionMatrix(double angle, double aspect, double near, double far)
{
double size = near * Math.Tan(MathUtils.DegreeToRadian(angle) / 2.0);
double left = -size, right = size, bottom = -size / aspect, top = size / aspect;
Matrix3D m = new Matrix3D(new double[,] {
{2*near/(right-left),0,(right + left)/(right - left),0},
{0,2*near/(top-bottom),(top+bottom)/(top-bottom),0},
{0,0,-(far+near)/(far-near),-(2 * far * near) / (far - near)},
{0,0,-1,0}
});
return m;
}
[/source]is there anything wrong here?
and the last question how do I use the camera matrix? Edited by Belos

Share this post


Link to post
Share on other sites
I don't know if it will help you, but you might read my Matrix tutorial. It's written for XNA and XNA does a lot of work for setting up you matrices for you. I haven't had to think about manually loading a matrix in a long time.

Here's the tutorial:

[url="http://xna-3d-101.com/Fundamentals/Matrices.html"]http://xna-3d-101.co...s/Matrices.html[/url]

It looks like you're working in C++ with DirectX. So, this may not be terribly helpful if you have to load your own matrices.

But Khan Academy has lessons on Matrices.

I swear that I saw a good video on YouTube on the subject of using Matrices in game creation the other day. I thought I book marked it, but apparently I didn't and I can't find it.

For 3D, you are going to be using 4 by 4 matrices.

The camera matrix (called a View Matrix in XNA) should store your camera position and facing.

Hopefully someone else will post something more helpful.

Post Script: Ah HA! I [b]found[/b] it. I think this guy does a pretty good job of explaining how matrices are loaded for 3D games.

[url="http://www.youtube.com/watch?v=4aiV5igZwVs&feature=related"]http://www.youtube.com/watch?v=4aiV5igZwVs&feature=related[/url] Edited by XNA-3D-101

Share this post


Link to post
Share on other sites
[color=#5A5A5A][font=tahoma, helvetica, arial, sans-serif][size=3][background=transparent]I used the following code to get the camera:[/background][/size][/font][/color]

[CODE] Matrix3D Camera
{
get
{
Vector3D cameraZAxis = -this.LookDirection;
cameraZAxis.Normalize();

Vector3D cameraXAxis = Vector3D.CrossProduct(this.UpDirection, cameraZAxis);
cameraXAxis.Normalize();

Vector3D cameraYAxis = Vector3D.CrossProduct(cameraZAxis, cameraXAxis);

Vector3D cameraPosition = (Vector3D)this.Position;
double offsetX = -Vector3D.DotProduct(cameraXAxis, cameraPosition);
double offsetY = -Vector3D.DotProduct(cameraYAxis, cameraPosition);
double offsetZ = -Vector3D.DotProduct(cameraZAxis, cameraPosition);

return new Matrix3D(new double[,]{{cameraXAxis.X, cameraYAxis.X, cameraZAxis.X, 0},
{cameraXAxis.Y, cameraYAxis.Y, cameraZAxis.Y, 0},
{cameraXAxis.Z, cameraYAxis.Z, cameraZAxis.Z, 0},
{offsetX, offsetY, offsetZ, 1}});
}
}

[/CODE]

[color=#5A5A5A][font=tahoma, helvetica, arial, sans-serif][size=3][background=transparent][background=transparent]The default camera matrix is[/background]
[background=transparent]{1,0,0,0},[/background]
[background=transparent]{0,1,0,0},[/background]
[background=transparent]{0,0,1,0},[/background]
[background=transparent]{-100,0,0,1}[/background]
[background=transparent]after I multiply the three matrices(the third is the model matrix) by the point and the resulting W in the point is very huge like -13000 [img]http://forum.codecall.net/public/style_emoticons/default/vbmodern/set1/scared.gif[/img] [background=transparent]so I am very confused right now!![/background][/background]
[background=transparent][background=transparent]the model matrix is[/background][/background]
[background=transparent][background=transparent]{0,0,0,100}[/background][/background]
[background=transparent][background=transparent]{0,0,0,100}[/background][/background]
[background=transparent][background=transparent]{0,0,0,100}[/background][/background]
[background=transparent][background=transparent]{0,0,0,1} [/background][/background]
[background=transparent]Can you tell me where I have gone wrong?[/background]
note: this is not xn[/background][/size][/font][/color] Edited by Belos

Share this post


Link to post
Share on other sites

This topic is 2035 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this