FPS mode improvements

[esper]

Sub-issue of #82

The FPS mode (first person view) is not really the normal FPS mode found in other games. The view is basically that the camera has move to the head of the player.

Suggested improvements (can be divided into smaller specific issues):

• Able to see the (current) weapon
• Have a cross aim
• Aim with the mouse movements also in the vertical axis
• The shoots should be originate from the weapon

[TheJosh]

I had an idea on the bus today for the crosshair (I do a lot of thinking on the bus). You could have a per-weapon image which is textured onto a quad (triangle strip) in the middle of the screen.

Then I started thinking about variable size crosshairs, based on some sort of accuracy figure which would vary between shots.

You could have it as the amount of randomness applied to the angle of the shot, in degrees. 0 = perfect accuracy. 50 = terrible. So then you would modify the weapon type config to have additional keys:

• best accuracy (e.g. 10)
• worst accuracy (e.g. 20)
• accuracy increase after fire (e.g. 2)
• accuracy recovery rate after fire per milisecond (e.g. 0.3)

As for the crosshair, you could define two sizes in pixels. The engine would map the smallest size to the best accuracy, and the largest size to the worst accuracy. Then the size of the quad could vary based on the accuracy value. Thus you would add three more keys:

• crosshair image
• crosshair min size (pixels)
• crosshair max size (pixels)

Of course, this is only one possible implementation for this kind of feature.

[TheJosh]

@esper, are you planning on making any of these changes? I did one of them by adding a simple crosshair, but feel free to commence this if you would like.

[esper]

@TheJosh, working on be able to aim in the vertical axis, no real progress yet.

[TheJosh]

Take a look at the calls to the WeaponType::doFire method from the unit class. There is a btTransform which contains the position (basis) and rotation of the unit.

You can tweak the angle using something like this:

btQuaternion rot = xform.getRotation() * btQuaternion(axis, angle);

where axis is a btVector3 and angle is in radians.

The actual weapons themselves use this line to tweak the horizontal axis to provide for a random angle for accuracy calculations:

btQuaternion rot = xform.getRotation() * btQuaternion(btVector3(0.0f, 1.0f, 0.0f), DEG_TO_RAD(angle));

[esper]

Thanks! I have found the doFire functions but had/have problems with the transforms. Will try your suggestion.