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littletray26

Direct3D 9 First Person Camera help?

4 posts in this topic

Hey, I'm new to gamedev.net and would love some help!

I've just started writing a game which I plan to be FPS. I've got the Camera class done which I'll dump the code for below.
I was just wondering if anyone could help me (like walk me through and explain each step) to convert this camera to a First Person Camera? Or link me to a tutorial that would? I started not long ago so I have a basic understanding of Vectors but I don't really understand anything like "normalizing" so I do need a bit of assistance [img]http://public.gamedev.net//public/style_emoticons/default/tongue.png[/img]

Also some basic tips on improving what I have and making it generally better. I'm a beginner so please go easy :3

Thanks!



===Camera.cpp===

[CODE]
//Camera source file
#include "Camera.h"
Camera::Camera(D3DXVECTOR3 pos, D3DXVECTOR3 lookAt, D3DXVECTOR3 up, float FOV, float aspect)
{
Camera::pos = pos;
Camera::lookAt = lookAt;
Camera::up = up;
D3DXMatrixPerspectiveFovLH(&projection, FOV, aspect, 0, 100);
}
void Camera::UpdateLook()
{
D3DXMatrixLookAtLH(&view, &pos, &lookAt, &up);
}
[/CODE]



===Camera.h===
[CODE]

//Camera header

#include "Main.h"

class Camera
{
private:
D3DXVECTOR3 pos;
D3DXVECTOR3 lookAt;
D3DXVECTOR3 up;

public:
D3DXMATRIX view;
D3DXMATRIX projection;

Camera(D3DXVECTOR3 pos, D3DXVECTOR3 lookAt, D3DXVECTOR3 up, float FOV, float aspect);
void UpdateLook();

};

[/CODE]



===Cameras place in main file
[CODE]

void Draw(LPDIRECT3DDEVICE9 rd3dDevice)
{
//Draw Code
camera.UpdateLook();
rd3dDevice->SetTransform(D3DTS_VIEW, &camera.view);
rd3dDevice->SetTransform(D3DTS_PROJECTION, &camera.projection);
}
[/CODE]
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If I was going to make a FPS camera class it would look something like yours but with a different internal representation of the look vector as spherical coordinates. This makes the logic for mouse-look much easier to understand and requires a simple spherical-to-Cartesian coordinate transformation whenever you construct the View matrix

[code]
// Camera.h
struct Camera
{
D3DXVECTOR3 Position;
float RotX;
float RotY;

D3DXMATRIX View;
D3DXMATRIX Proj;

Camera(D3DXVECTOR3& position, float fov, float aspect);
void Update();
};
[/code]

[code]
// Camera.cpp
Camera::Camera(D3DXVECTOR3& position, float fov, float aspect)
{
Position = position;
RotX = 0;
RotY = 0;
D3DXMatrixPerspectiveFovLH(&Proj, fov, aspect, 0, 100);
}
void Camera::Update()
{
POINT mousePos;
GetCursorPos(&mousePos);
SetCursorPos(640, 480);
RotX += (float)(mousePos.y - 480) / 500.f;
RotY += (float)(mousePos.x - 640) / 500.f;
// change 500.f to any value to adjust sensitivity
// change += to -= if it rotates the wrong way
D3DXVECTOR3 look = D3DXVECTOR3(cosf(RotY) * sinf(RotX), cosf(RotX), sinf(RotY) * sinf(RotX));
D3DXVECTOR3 target = Position + look;
D3DXVECTOR3 up = D3DXVECTOR3(0, 1, 0);
D3DXMatrixLookAtLH(&View, &Position, &target, &up);
}
[/code]
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Hey Hupsilardee, could you tell me what this part of your code means/does?

Thanks for replying :)

[quote name='hupsilardee' timestamp='1338194174' post='4943935']
D3DXVECTOR3 look = D3DXVECTOR3(cosf(RotY) * sinf(RotX), cosf(RotX), sinf(RotY) * sinf(RotX));
[/quote] Edited by littletray26
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First, did the code work as you want?

[url="http://en.wikipedia.org/wiki/Spherical_coordinates"]http://en.wikipedia.org/wiki/Spherical_coordinates[/url]

Basically, instead of storing a vector that tells me the direction the camera is looking, I store two angles - one is the "up/down" angle and the other is the "left/right" angle. In a spherical coordinate system, there is a third number - r, the distance from the origin - but that is always 1 in this case so I leave it out.

The advantage of storing the angles rather than the vector are that it is very easy to adjust the up/down/left/right angles through which the camera is looking - as you can see, I use the mouse like most FPS games do.

Now, to build the View matrix I need to pass in a target vector, described by the camera position + look vector, so I need to calculate the look vector from the spherical coordinates (RotX, RotY, 1). That line of code gives the look vector in terms of RotX and RotY (multiplied by r = 1)
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[quote name='hupsilardee' timestamp='1338199227' post='4943950']
First, did the code work as you want?
[/quote]

Nope, I tried it out and it didn't do anything. The camera stayed in one place. I may have put it in wrong but I'm not sure. I'd dump the code but I'm at school.
I'll have another look at it when I get home and I'll let you know :)
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