Steven TY : VFX

25 octobre 2018

3 mai 2018

Explosion exploration no particles

Here is a exploration for a cartoon explosion done without using any particles

For this exercise, I've created a mesh in Houdini.

I simply created a fire simulation, converted it in vdb, converted the vdb in polygons and remeshed it to "save" some vertex.

After that, I made a shader only using math to create the animation and dissolve effect

15 mars 2018

I wanted to try some Houdini fluid and test how i could bring that into a game engine.
My goal was to bake the velocity information into the vertex so i wouldn't have to bake the velocity in a texture.

I started by creating a fluid simulation in Houdini.
For that i exported a part of my world from the engine and imported it in Houdini.

Just using a bunch of mesh to create my sim was not great so i decided to create a shell from all those meshes.

Here i am using a ray with a high density plane but converting all mesh to VDB then converting it back to poly could be a better solution.

After creating my fluid i picked a frame i liked and converted it to a mesh (using remesh so i could control the mesh cost)

I then used the particle data to calculate my velocity and other attribute for foam.

Once i calculated my velocity i pushed the value into the vertex.

And i made a shader using the vertex color to control how the texture will flow.
I also added some vertex animation to get a better result.

Conclusion:
It works, that's great but the process is quite heavy.
Having information in the vertex means that Lods can create issues, also the mesh needs to have enough density to have the information.

2 juin 2016

Rain using vertex animation

My goal was to create a rain effect around lights without using particles to save CPU time

So i started this idea using a simple mesh with a vertex animated shader to avoid unnecessary overdraw

I am using a simple mesh with a few planes, i order to rotate the planes to look at the camera at all time i am using the Spline thicken function in unreal to get all the planes to be align with the camera.
I could have made cross mesh and made the shader a bit cheaper but the Spline thicken function allow me to change the length of the rain in the material.

Then i used a the vertex animation to get the motion in local space. the solution was OK but i was lacking variation in the motion. so i decided to use vertex color to control the speed and time offset.

After that i decided the add more timing variation using the mesh pivot point

I am using the blue channel to add more speed and i am using the red channel to add some timing offset.

After that i wanted more variation so i added a rotation on the mesh, unfortunately it did not play well with the spline thicken function. I ended up with some moment with the rotation when the all the plane were badly align with the camera.

I could have added some rotation to the base mesh to avoid that but it wouldn't have work with the spline thicken well.