You can follow along with the explanation below by opening example '01_Moving_particles_with_textures.toe'. To start simply, we're going to generate 1000 points at the origin 0,0,0. Similarly if we wanted a particle system with 1,000,000 points, we would need a piece of geometry with 1,000,000 points. For the particle system this means that we need a piece of geometry with 1000 points to have a particle system with 1000 points. It is simply a bit of code that gets applied onto every point that is given to it. As mentioned earlier, a GLSL MAT cannot create particles on its own. The first thing we need to do is create a set of points that will be used by the GLSL MAT as the particles. Move the incoming points from using all the above steps Sample the Noise TOP texture and create UV co-ordinates Get the pointIndex, point position texture, and then the points per instance ![]() Use a Noise TOP to create 1000 RGBA channels to use as point positionsĬreate a GLSL TOP to scale the values of the Noise TOP (will be built upon later after we remove the noise)Ĭreate a GLSL Mat that will hold all of the shader code for the particlesĬreate a basic pixel shader to shade all pixels whiteĬreate a vertex shader with uniform inputs and correct outputs 12.7.2 Moving Particles with Texturesīefore getting started, this is an outline of the steps to this section:Ĭreate a set of points that will be your initial positions To achieve the goal of creating a fully-functioning GPU particle system, we will break the particle system into a number of incremental projects. In TouchDesigner, this be solved by using a simple feedback loop. In other OpenGL applications, you'd create multiple texture buffers that you would ping-pong between reading and writing. This is important because the particles in a particle systems need to know their previous position at last compute, so that they can then re-apply their code to compute their new position on the next frame. A uniform is a parameter or value that you will pass to your shader code. All the shader code will need to be standalone and any referential data will need to be fed to the shader as either a texture or value uniform. The shader will not have a reference of the previous or next frame, and wont have any reference to any points that have been computed on that same frame. The amount of points feeding in determine the number of times our material shader will compute and the shader code we write will be applied to every single particle individually.Ī second important concept to remember is that similar to any other type of shader, your code has no reference to anything other than the current point it is processing. One concept to understand is that the GLSL material shader we'll be using cannot create new points out of thin air, so you have to feed it a set a starting points that correspond to the maximum number of particles in your system. The process to achieve a particle system in GLSL can be slightly confusing at first, compared to just creating a Particle SOP, but once you understand the basic principles behind the workflow, you will have infinite freedom to experiment. GLSL shaders allow for the creation of particles systems with extremely large particle counts (in the multi-millions and more), with customized behaviour, that still compute quickly. This has many benefits compared to using the built-in Particle SOP, because all the computations inside of GLSL shader are performed on the GPU. This tutorial will be focused on creating a GPU based particle system using TouchDesigner and GLSL shaders. ![]() Outputting Content for Deployment and Performanceġ2.7 GPU Particle Systems 12.7.1 Introduction
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