Advanced video programming with Jitter

In this workshop, you will learn to build incredible live videos with particles systems, using Max and Jitter.

Cycling’74 has recently released GL3, which ties together more closely Jitter with Open GL, and optimises use of the GPU. With this recent update available in the package manager, you can build highly performance videos without having to code them in C++. See an overview of videos built with GL3 below:

– Introduction to GL3 features

– Quick overview of most of the examples in the GL3 package

– Build a simple particle system from scratch

– Explorations with gravity/wind

– Exploration with target attraction

- Review of Vectors and Forces

- Introducin shaders uniform parameters

- Particles attracted to target

- Introduction to the render shader

- Changing particles color through the TF shader 

- Use billboards for the particles 

- In the Render_Shader: transform the number used to set the particles size (the multiplier for the jit_JollyBuffer.x) into a uniform parameter, so you can modify it from the patch. 

- Implement the attraction force to the target in this way:
  vec3 directionToTarget = targetPosition - iPosition;
  float distanceFromTarget = length(targetDirection);
  distanceFromTarget = clamp(distanceFromTarget, 1.0, 10.0);
  vec3 attractionForce = normalize(directionToTarget);
  float G = 0.0002;
  float attractorMass = 1.0;
  float forceStrength = (G*mass*attractorMass) / (distanceFromTarget*distanceFromTarget);
  attractionForce *= forceStrength;

- Transform the G factor (the attraction strength) into a uniform parameter modifiable from the patch. 

- Change the colors of the particles according to their velocity.
  In order to do this you will have to modify the oColor using the iVelocity or the prevVelocity variable. 

- If you want to refresh your memory you can watch this video I recently made on the application of forces to particles: https://youtu.be/GoywMZFC8Ns

Hey all!
Here are the assignment for next Tuesday: 

00 - OPTIONAL: join the Discord channel I created specifically for the workshop:
https://discord.gg/XcPZMTrYvs

01 - Modify the size of the particles according to their remaining life-time: the lower the life-time the smaller should be the particle, until it disappears when the life-time reaches the zero.

(HINT: modify the "gl_PointSize" variable in the render shader using also the y component of the "jit_JollyBuffer", which contains the life-time.)

02 -  Visualize the "high friction area" we implemented in Session 03 using a jit.gl.gridshape @shape sphere.
It must be transparent in order for us to see the particles beneath it.

(HINT: you can either use the transparency with "@blend_enable 1" or you can use the "@poly_mode" attribute to make  the sphere "see-through".

03 - Can you add a "black edge" to the particles circles?
Yes you can! In order to do this you will need to modify the fragment program in the render shader.
For the moment it looks like this:

float lenCoords = length(gl_PointCoord-0.5);

    if (lenCoords >= 0.5) 

    {

        discard;

    }

So you can have an "if else" statement that says something like:

    else if (lenCoords >= 0.3)

    {

    }

 Complete the statement by filling the space between the curly brackets so the particles will have a black edge.
Also explain why this works. 

04 - Add at least another attractor and make its position modifiable by a uniform parameter.
Change the G factor of each attractor so they have a different gravity strength.