Back in the old days PSX games had a shaky and wobbly effect of vertices, this unwanted effect is caused by the lack of floating point precision.
The PSX’s hardware only allow fixed point calculation so when the camera is moving or an object is moving, any given vertex stays in its position until it’s close to the next position and suddenly snap to it, nowadays graphics hardware can interpolate vertices between two position smoothly thanks to more floating point precision that is available.
We assume you have already created a project ready to test the shader or you already have a project that you want to apply the effect in it. The minimum you must have is a mesh with material applied to it.
You can download the complete project at the end of this tutorial so you can check it at your own pace, you will find everything documented.
Step 1: Create a material parameter collections
Material parameter collections is an asset that store global parameters (a set of scalar and vector parameters) that you can reference in any material. For example wind direction and strength can be referenced by all foliage’s materials. To read more, check this link.
To create a new material parameter collections assets, in content browser right click and go to Materials & Textures > Material Parameter Collection.
Next add two scalar parameters, Global_PSXEffect_3dGridCellSize & Global_PSXEffect_PixelizationAmount
Hit save and close the window.
Step 2: Create material function
The function PSXEffect_Function return a vertex offset data, we use it to offset vertices for the shaky effect. The function also pixelate UV data, we plug the return value in Texture Sample node to have a pixelated texture.
Notice that we used the parameters we created previously in material parameter collections.
To understand how we shake the vertices, imagine a 3D grid around your mesh, and vertices snaps the the closest points in that grid.
Step 3: Add PSXEffect_Function to you materials
It’s easy to add a function to a material. You can add it by left click in the material editor and type the name of the function.
You will find the source files of this effect here.
That’s all folks ! Thanks for reading. If you have any questions drop a comment here or join me on Discord.