VFX Quick Tip: How to Stretch Particles Based on Velocity

If you're creating a real-time effect with particles, you can make the particles stretch based on their velocity. Here's how to do it!

How to Stretch VFX Particles Based on Velocity

Start building the velocity stretch within your material.

• add 'Particle Direction' node
• add 'World Position' node and make sure it is set to 'absolute'
• add 'Particle Position' and 'Particle Speed' node

‍

Subtract Particle position from World position and then normalize, and normalize Particle Direction as well.

Add a 'transform' node, and change it from world space to camera space. Plug the normalized particle direction into it.

Duplicate the transform node, and plug the normalized/subtracted world and particle position into it.

Dot product the two transform nodes.

Create a dynamic parameter and rename the first two elements to 'MaxVelocityInfluence' and 'VelocityStretchMult' giving them a default value of 1000 and 0.1.

Clamp the particle speed with the max being the 'MaxVelocityInfluence' from the Dynamic Parameter node, leaving the min at the default of 0.

Create a multiply node and multiply the clamped particle speed with the 'VelocityStretchMult' from the Dynamic Parameter node.

Duplicate the multiple node twice.

Connect the outputs of the dot product and the first multiple into the inputs of the second multiply node.

Connect the outputs of the second multiply node and the normalized particle direction into the inputs of the third multiply node.

Connect the output of the third multiply node into the 'World Position Offset' in the material, then save or apply.

In your particle system, add a 'Dynamic Material Parameters' module in particle update, and set your MaxVelocityInfluence and VelocityStretchMult to something desirable.

And you're done!

‍

‍Want to stay in touch with our studio as we craft world-class real-time VFX? Follow Beyond-FX on Twitter, Instagram, Facebook, YouTube, Twitch, & TikTok!