Emission and shape modules in Unity - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Unity particle emission code?

Consider the following Unity C# code snippet that configures a particle system's emission module:

var ps = GetComponent<ParticleSystem>();
var emission = ps.emission;
emission.rateOverTime = 10f;
Debug.Log(emission.rateOverTime.constant);

What will be printed in the console?

Unity

var ps = GetComponent<ParticleSystem>();
var emission = ps.emission;
emission.rateOverTime = 10f;
Debug.Log(emission.rateOverTime.constant);

A 10

B 10.0f

C 0

D Error: Cannot access rateOverTime.constant

💡 Hint

Remember that rateOverTime is a MinMaxCurve and .constant returns the float value.

The emission.rateOverTime property is a MinMaxCurve. Setting it to 10f sets a constant rate of 10 particles per second. Accessing .constant returns the float 10.

❓ Predict Output

intermediate

What shape does this Unity particle system use?

Given this code snippet configuring the shape module of a particle system:

var ps = GetComponent<ParticleSystem>();
var shape = ps.shape;
shape.shapeType = ParticleSystemShapeType.Cone;
shape.angle = 25f;
shape.radius = 0.5f;
Debug.Log(shape.shapeType);

What will be the output in the console?

Unity

var ps = GetComponent<ParticleSystem>();
var shape = ps.shape;
shape.shapeType = ParticleSystemShapeType.Cone;
shape.angle = 25f;
shape.radius = 0.5f;
Debug.Log(shape.shapeType);

A Cone

B Sphere

C Circle

D Box

💡 Hint

Look at the shapeType property assigned.

The shapeType property is set to ParticleSystemShapeType.Cone, so the output is 'Cone'.

🔧 Debug

advanced

Why does this emission rate code cause an error?

Examine this Unity C# code snippet:

var ps = GetComponent<ParticleSystem>();
var emission = ps.emission;
emission.rateOverTime = new ParticleSystem.MinMaxCurve(5f, 10f);
Debug.Log(emission.rateOverTime.constant);

What error will occur when running this code?

Unity

var ps = GetComponent<ParticleSystem>();
var emission = ps.emission;
emission.rateOverTime = new ParticleSystem.MinMaxCurve(5f, 10f);
Debug.Log(emission.rateOverTime.constant);

A NullReferenceException

B No error, prints 5

C SyntaxError

D InvalidOperationException: Cannot access constant when curve mode is TwoConstants

💡 Hint

Check what happens when MinMaxCurve uses two constants.

When MinMaxCurve is set with two constants, its mode is TwoConstants. Accessing .constant throws InvalidOperationException because .constant is undefined in this mode.

🚀 Application

advanced

How to configure a particle system to emit particles only from a sphere surface?

You want a Unity particle system to emit particles only from the surface of a sphere, not inside it. Which shape module settings achieve this?

A Set shapeType to Hemisphere and disable 'Emit from Shell' option

B Set shapeType to Sphere and set radius; disable 'Emit from Shell' option

C Set shapeType to Sphere and enable 'Emit from Shell' option

D Set shapeType to Cone and enable 'Emit from Shell' option

💡 Hint

Check the 'Emit from Shell' option in the shape module.

Enabling 'Emit from Shell' on a Sphere shape makes particles emit only from the surface (shell) of the sphere.

🧠 Conceptual

expert

What is the effect of changing emission.rateOverTimeMultiplier at runtime?

In Unity, if you change emission.rateOverTimeMultiplier during gameplay, what happens to the particle system's emission?

A The emission rate changes only after restarting the particle system

B The emission rate instantly changes to the new multiplier times the base rate

C The emission rate does not change at runtime

D Changing rateOverTimeMultiplier causes the particle system to stop emitting

💡 Hint

Think about how multipliers affect emission rate dynamically.

Changing emission.rateOverTimeMultiplier at runtime immediately affects the emission rate by multiplying the base rate, allowing dynamic control.