Continuous Laser

Download Code File

Discussion:
This resource uses the Torque Laser Beams resource as a starting point. So much appreciation is given to Robert Brower. The issues that I have with the previous resource are: no control of beam duration, long lived beams stop being attached to the weapon, firing at close range doesn't even display a beam.

To fix theses issues, I recreated the resource, removed a lot of unnecessary code, and made a small change to the projectile code. All issues with the previous resource are all connected to the fact that the laser projectile was "fired" from the weapon and "destroyed" upon collision. This resource allows the user to set the maximum length and duration of the laser beam. Also, the default projectile "forgets" its source object (to enable damaging the firer) after 7 ticks. To allow the laser to "remember" the originating object, I had to remove the constant and replace it with a variable.

To save network traffic, the laser is a single object that is moved each tick to align it with the targeting point. As such, it does not "explode" as the explosion method destroys the object. Instead the "particleEmitter" is used at the end of the beam. "Oncollision" is still called every tick to allow damage based on collision duration.

Comments:
I do not use "onCollision" to deal damage for this weapon because the points add up really fast. Instead, I check the firepoint "onFire" and deal damage just before creating the "projectile".

if (%scanTarg) {
    %targetId = getWord(%scanTarg,0);
    %targetPoint = getWords(%scanTarg,1,3);
    if (%targetId.getType() & $TypeMasks::ShapeBaseObjectType) {
      %targetId.damage(%obj,%targetPoint,%this.damage,"Laser");
    }
  }

There was an issue of object sorting when rendering since sometimes the beams are rendered behind the current scene sometimes (i.e. not visibly rendered), I have solved it by forcing the rendering even if not visible.
There was also an alpha problem carried over from the original resource when the beam overlaps a water block, I have fixed it in the prepRender function.

Key:
I use the same indication of modifications as a patch file. A line beginning with a "-" is to be removed and a line beginning with a "+" is to be added. Be sure to remove the "+" when you actually put the line into your code. A few lines around the changes are shown to give context to the changes. The triple dot "..." is showing that information has been removed for brevity purposes.

Development Environment:
June 2005
Head 1.2.2
Win32
Single Player

Implementation:
EngineFile: /console/consoleTypes.h

enum ConsoleDynamicTypes {

...
   TypeTriggerPolyhedron,

   TypeProjectileDataPtr,

+   TypeLaserDataPtr,

   TypeCannedChatItemPtr,

...

EngineFile: /game/projectile.h

class ProjectileData : public GameBaseData
{
...
public:
   // variables set in datablock definition:
   // Shape related
   const char* projectileShapeName;

+   U32 SourceIdTimeoutTicks;              ///< Time until Projectile can damage creator
...

class Projectile : public GameBase
{
   typedef GameBase Parent;
   ProjectileData* mDataBlock;

   SimObjectPtr<ShapeBase> mTarget; 
   S32 mTargetId; 

public:
   // Initial conditions
   enum ProjectileConstants {
-      SourceIdTimeoutTicks = 7,   // = 231 ms
      DeleteWaitTime       = 500, ///< 500 ms delete timeout (for network transmission delays)
      ExcessVelDirBits     = 7,
      MaxLivingTicks       = 4095,
   };
...

EngineFile: /game/projectile.cc

ProjectileData::ProjectileData()
{
   projectileShapeName = NULL;
+   SourceIdTimeoutTicks = 7;
...

void ProjectileData::initPersistFields()
{
   Parent::initPersistFields();

   Con::registerType("ProjectileDataPtr", TypeProjectileDataPtr, sizeof(ProjectileData*),
                     REF_GETDATATYPE(ProjectileData),
                     REF_SETDATATYPE(ProjectileData));

+   addNamedFieldV(SourceIdTimeoutTicks, TypeS32, ProjectileData, new IRangeValidatorScaled(TickMs, 0, Projectile::MaxLivingTicks));

   addNamedField(particleEmitter,  TypeParticleEmitterDataPtr, ProjectileData);
...

void ProjectileData::packData(BitStream* stream)
{
...
+   stream->writeRangedU32(SourceIdTimeoutTicks, 0, Projectile::MaxLivingTicks);
   stream->writeRangedU32(lifetime, 0, Projectile::MaxLivingTicks);
   stream->writeRangedU32(armingDelay, 0, Projectile::MaxLivingTicks);
   stream->writeRangedU32(fadeDelay, 0, Projectile::MaxLivingTicks);
...

void ProjectileData::unpackData(BitStream* stream)
{
...
+   SourceIdTimeoutTicks = stream->readRangedU32(0, Projectile::MaxLivingTicks);
   lifetime = stream->readRangedU32(0, Projectile::MaxLivingTicks);
   armingDelay = stream->readRangedU32(0, Projectile::MaxLivingTicks);
   fadeDelay = stream->readRangedU32(0, Projectile::MaxLivingTicks);
...

void Projectile::processTick(const Move* move)
{
   Parent::processTick(move);

   mCurrTick++;
-   if(mSourceObject && mCurrTick > SourceIdTimeoutTicks)
+   if(mSourceObject && mCurrTick > mDataBlock->SourceIdTimeoutTicks)
   {
      mSourceObject = 0;
      mSourceObjectId = 0;
   }
...

ScriptFile: /server/scripts/crossbow.cs

-datablock ProjectileData(CrossbowProjectile)
+datablock LaserData(CrossbowProjectile)
{
...
-   lifetime            = 5000;
-   fadeDelay           = 5000;
+   lifetime = 100;
+   fadeDelay = 100;
...
+   beamStartRadius = 0.1;
+   beamEndRadius = 0.1;
+   materialList = "~/data/shapes/laserbeam/red.dml";
+   interval = 0;
}
...

datablock ShapeBaseImageData(CrossbowImage)
{
...
+  maxRange = 500; // maximum range in meters
...

function CrossbowImage::onFire(%this, %obj, %slot)
{
   %projectile = %this.projectile;

   // Decrement inventory ammo. The image's ammo state is update
   // automatically by the ammo inventory hooks.
   %obj.decInventory(%this.ammo,1);

-   // Determin initial projectile velocity based on the 
-   // gun's muzzle point and the object's current velocity
-   %muzzleVector = %obj.getMuzzleVector(%slot);
-   %objectVelocity = %obj.getVelocity();
-   %muzzleVelocity = VectorAdd(
-      VectorScale(%muzzleVector, %projectile.muzzleVelocity),
-      VectorScale(%objectVelocity, %projectile.velInheritFactor));

+  //Determine how far should the picking ray extend into the world?
+  %selectRange = %this.maxRange;
+  %eyeVector = %obj.getEyeVector();
+  %eyePoint = %obj.getEyePoint();
+  // scale eye vector to the range the player is able to fire
+  %eyeScaled = VectorScale(%eyeVector, %selectRange);
+  // targetpoint = eye point + length of selectable range
+  %targetPoint = VectorAdd(%eyePoint, %eyeScaled);
+  // Everything mask
+  %mask = $TypeMasks::StaticObjectType|$TypeMasks::EnvironmentObjectType|$TypeMasks::TerrainObjectType|$TypeMasks::InteriorObjectType|$TypeMasks::WaterObjectType|$TypeMasks::TriggerObjectType|$TypeMasks::MarkerObjectType|$TypeMasks::GameBaseObjectType|$TypeMasks::ShapeBaseObjectType|$TypeMasks::CameraObjectType|$TypeMasks::StaticShapeObjectType|$TypeMasks::PlayerObjectType|$TypeMasks::ItemObjectType|$TypeMasks::VehicleObjectType|$TypeMasks::VehicleBlockerObjectType|$TypeMasks::ProjectileObjectType|$TypeMasks::ExplosionObjectType|$TypeMasks::CorpseObjectType|$TypeMasks::DebrisObjectType|$TypeMasks::PhysicalZoneObjectType|$TypeMasks::StaticTSObjectType|$TypeMasks::StaticRenderedObjectType|$TypeMasks::DamagableItemObjectType;

+  %scanTarg = ContainerRayCast (%eyePoint, %targetPoint, %mask, %obj);
   
+  if (%scanTarg) {
+    %targetPoint = getWords(%scanTarg,1,3);
+  }

   // Create the projectile object
   %p = new (%this.projectileType)() {
      dataBlock        = %projectile;
-      initialVelocity  = %muzzleVelocity;
+      initialVelocity  = "0 0 0";
-      initialPosition  = %obj.getMuzzlePoint(%slot);
+      initialPosition  = %targetPoint;
      sourceObject     = %obj;
      sourceSlot       = %slot;
      client           = %obj.client;
+      range = %this.maxRange;
   };
   MissionCleanup.add(%p);
   return %p;
}

Included files:
Create directory /data/shapes/laserbeam.
Copy red.dml and red_beam.png to that directory.
Copy laser.cc to /engine/game directory
Recompile engine

Credits:
Derk Adams - adamsderk@hotmail.com