Car Explosions

Introduction

This tutorial will explain how to create an explosion effect for an automobile. You will require basic knowledge of the Valve Hammer Editor. This tutorial is not hard to follow and is an extended function of trigger_push.

The Car

To start, create a prop_physics_override with the following settings.

• Name: Car1
• World Model: (In the prop_vehicles folder, choose a car with a physic model.)
• MinDamageToHurt: 90 (explained later)

Once the vehicle is created, it must be place above the ground level.

In order to add more realism and interactivity, a fuel tank should be placed close to the car that will explode if shot.

Create a brush on the car wherever the fuel tank may be located, choose a good texture for a fuel tank and make the fuel tank a func_breakable.

• Name: FuelTankCar1
• Parent: Car1
• MaterialType: Metal

For design purposes, the fuel tank may be a cylinder or another similar shape.

The Effects

Create five env_explosion entities and place them at five points around the vehicle, like on a die, i.e. the sides, front, back, and bottom.

• Name: ExplosionCar1
• Parent: Car1
• Magnitude: 100

Then create an env_physexplosion entity at the center of the vehicle.

• Name: PhysExplosionCar1
• Parent: Car1
• Magnitude: 500

Create an env_smokestack entity and place it where the smoke will be emitted.

• Name: SmokeCar1
• Parent: Car1
• Color: You may choose any color you wish.

The Thrust

Though there are several explosion entities in place surrounding the car, it is still not enough to lift the car due to its weight.

Create a brush at the center of the vehicle and make it large enough to encompass the top side while starting from the bottom. Apply the trigger texture and TieToEntity trigger_push. The car will fly as high as the trigger is configured.

• Name: PushCar1
• Parent: Car1
• PushDirection: Up
• StartDisabled: Yes
• Speed: 1500
• Flags: OnlyOnce, Physics, Pushables

Please make sure the Client flag is not enabled.

The Outputs

At this point, the explosion effect will not work. The outputs of the car entity must now be configured in order for this to happen.

First, go in the car's properties.

MinDamageToHurt allows entities to ignore all damage less than a specified amount and 90 is best for explosions like grenades and rockets.

The outputs of the car entity should be as followed:

Car Outputs

	My Output	Target Entity	Target Input	Parameter	Delay	Only Once
	OnHealthChanged	ExplosionCar1	Explode	<none>	0.00	Yes
	OnHealthChanged	PhysExplosionCar1	Explode	<none>	0.00	Yes
	OnHealthChanged	PushCar1	ClearParent	<none>	0.00	Yes
	OnHealthChanged	PushCar1	Enable	<none>	0.00	Yes
	OnHealthChanged	SmokeCar1	TurnOn	<none>	0.00	Yes
	OnHealthChanged	FuelTankCar1	Break	<none>	0.00	Yes

The car will now ignore damage less than 90 and therefore, when a damage amount above 90 is applied to the car, the explosions ignite, the smoke starts, the fuel tank is destroyed, and the trigger_push entity loses its parents. If it is still parented to car1, the entity would pursue the car up in an infinite cycle.

To destroy the Fuel Tank, the outputs of the car can be reused with OnHealthChanged changed to OnBreak to destroy it, like so:

Fuel Tank Outputs

	My Output	Target Entity	Target Input	Parameter	Delay	Only Once
	OnBreak	ExplosionCar1	Explode	<none>	0.00	Yes
	OnBreak	PhysExplosionCar1	Explode	<none>	0.00	Yes
	OnBreak	PushCar1	ClearParent	<none>	0.00	Yes
	OnBreak	PushCar1	Enable	<none>	0.00	Yes
	OnBreak	SmokeCar1	TurnOn	<none>	0.00	Yes

The car outputs are not disabled by the fuel tank explosion such that the explosions would inflict damage to the car and cause a second explosion for added effect.

The map can now be compiled and tested.