How to Make Models Pitch

As we know the BUILD Engine has limits, such as that it can not pitch 2D sprites (think of a picture hanging on a wall crooked) but we can exploit this by using 3D models plus the structure members pitch and roll.

It is best to use the code as a state so that every actor is not using it, otherwise it could have a serious impact on your frame rate, not to mention that certain actors would just look bad using this code.

The following code will allow actors that call the state to pitch and roll if they are placed or move onto a sloped surface.

Note: This code should be placed at the top of GAME.CON or at least written first before any actors call the state.

First off, we will need the following gamevars:

gamevar a	0 0
gamevar b	0 0
gamevar x	0 0
gamevar y	0 0
gamevar z	0 0
gamevar angle	0 0
gamevar SECTOR	0 0

Then, we need to define two things:

define TILT_SPEED 32
define TILT_MAX 128 // This value may be edited if more sloping is required.

Next, the code itself:

state pitchroll {
	iffloordistl 8
	{
		// get z behind? actor
		getactor[THISACTOR].x x
		getactor[THISACTOR].y y
		getactor[THISACTOR].z z
		getactor[THISACTOR].ang angle
		getactor[THISACTOR].clipdist a
		mulvar a -1 addvarvar a x
		rotatepoint x y a y angle x y
		updatesectorz x y z SECTOR
		ifvarn SECTOR -1 { //make sure calculated point is in a SECTOR
			getflorzofslope SECTOR x y b
		} else {
			getactor[THISACTOR].z b
		}
		// get z in front? of actor
		getactor[THISACTOR].x x
		getactor[THISACTOR].y y
		getactor[THISACTOR].clipdist a
		addvarvar a x
		rotatepoint x y a y angle x y
		updatesectorz x y z SECTOR
		ifvarn SECTOR -1 {
			getflorzofslope SECTOR x y z
		} else {
			getactor[THISACTOR].z z
		}

		// get pitch amount
		subvarvar z b
		shiftvarr z 3
		
		// cap amount of pitch, Duke looks silly leaning out so far
		ifvarg z TILT_MAX setvar z TILT_MAX
		setvar a TILT_MAX mulvar a -1
		ifvarvarl z a setvarvar z a
		
		// gradually adjust pitch to avoid jerkily snapping to the slope
		getactor[THISACTOR].pitch a
		ifvarvarg a z {
			subvar a TILT_SPEED
			setactor[THISACTOR].pitch a
		} else ifvarvarg a z {
			setactor[THISACTOR].pitch z
		}
		ifvarvarl a z {
			addvar a TILT_SPEED
			setactor[THISACTOR].pitch a
		} else ifvarvarl a z {
			setactor[THISACTOR].pitch z
		}	
		
		// get z right? of actor
		getactor[THISACTOR].x x
		getactor[THISACTOR].y y
		getactor[THISACTOR].z z
		getactor[THISACTOR].ang angle
		getactor[THISACTOR].clipdist a
		addvarvar a y
		rotatepoint x y x a angle x y
		updatesectorz x y z SECTOR
		ifvarn SECTOR -1 {
			getflorzofslope SECTOR x y b
		} else {
			getactor[THISACTOR].z b
		}
		
		// get left? of actor
		getactor[THISACTOR].x x
		getactor[THISACTOR].y y
		getactor[THISACTOR].clipdist a
		mulvar a -1 addvarvar a y
		rotatepoint x y x a angle x y
		updatesectorz x y z SECTOR
		ifvarn SECTOR -1 {
			getflorzofslope SECTOR x y z
		} else {
			getactor[THISACTOR].z z
		}

		// get roll amount
		subvarvar z b
		shiftvarr z 3
		
		// cap amount of roll
		ifvarg z TILT_MAX setvar z TILT_MAX
		setvar a TILT_MAX mulvar a -1
		ifvarvarl z a setvarvar z a
		
		// gradually adjust roll
		getactor[THISACTOR].roll a
		ifvarvarg a z {
			subvar a TILT_SPEED
			setactor[THISACTOR].roll a
		} else ifvarvarg a z {
			setactor[THISACTOR].roll z
		}
		ifvarvarl a z {
			addvar a TILT_SPEED
			setactor[THISACTOR].roll a
		} else ifvarvarl a z {
			setactor[THISACTOR].roll z
		}
	}
}
ends

Finally, to make use of the state, place the following line into any actor that will use it. For example, I will use the chaingun pickup.

actor CHAINGUNSPRITE
  fall
  state pitchroll // This is where I have placed the state.
  ifmove RESPAWN_ACTOR_FLAG
    state respawnit
  else
    ifp pshrunk nullop
    else
      ifp palive
        ifpdistl RETRIEVEDISTANCE
          ifcount 6
            ifcanseetarget
      {
        ifgotweaponce 0
          break

        addweapon CHAINGUN_WEAPON 50
        quote 54
        ifspawnedby CHAINGUNSPRITE
          state getweaponcode
        else
          state quikweaponget
      }
enda