Question

Hi i am using DirectX 10 and C++ to make a very simple first person shooter just a gun and targets, i have the gun and the target and the gun shoots bullets in the corrct direction etc.

however i cannot get the camera to be locked on the gun and looking at the crosshairs,
for the camera i have this

vecEye.x = g_f_GunX;
vecEye.y = g_f_GunY + 3;
vecEye.z = g_f_GunZ - 5.0;


vecAt.x = g_f_CrossX;
vecAt.y = g_f_CrossY;
vecAt.z = g_f_CrossZ;

g_Camera.SetViewParams( &vecEye, &vecAt );

for the purpose of this my crosshair is just an object that is infront of the gun and it moves with the gun, i have put the code for the camera in the ‘onFrameRender’ method

it is my assumption that this code should put the camera just behind my gun and when the gun (and crosshairs) are moved the camera should be looking at the crosshairs all the time in the center of the screen, however on running it the camera is not doing this at all and doesnt move with gun or crosshairs at all

any help would be much appriciated

Answer 1

for the purpose of this my crosshair is just an object that is in front of the gun and it moves with the gun

That’s not going to work unless “eye” is located directly behind the gun barrel (gun will block the view) – if “eye” is even slightly above gun, you’ll end up looking at ground through the crosshair object, and view direction won’t match camera direction at all.

Several ways to deal with it:

1. Draw crosshair in the middle of screen as 2d shape, shoot bullets from the camera, and draw gun model just for show. I think that was fairly common way to do it in the “old days” (doom 1 and such)
2. Draw crosshair in the middle of screen as 2d shape. Make a collision detection sensor (ray) that starts at the camera position, and points in same direction as camera. When user presses “fire” run a collision query using this ray sensor, and if it hits anything, fire gun at that point. That’s the only real way to deal with aiming if you’re writing 3rd person shooter.
3. Remove cross-hair and user laser pointer/sight to aim the gun (Might look cool), shoot bullets from gun. Laser pointer ray should originate from gun, of course. This was used in zero tolerance, avp and few other games.

Also in 3d shooters camera orientation is frequently stored as a yaw/pitch/roll combination of angles.