Hello everyone,
Today I'm excited to share a robust method for flex control that's both powerful and user-friendly—with no coding required! This approach allows you to dynamically disintegrate or fluidify your point cloud on demand, while ensuring everything seamlessly falls back into place. Best of all, you gain precise control over each individual point through custom point weights.
Below is an overview of how the system works:
The Core Concept
The key to this system is managing the velocity of each particle. Here’s the basic terminology:
- A = Acceleration
- V = Velocity
- P = Position
- D = Delta time (1/fps)
The Process
- Velocity Update:The particle's velocity is updated by adding the acceleration:
- V = V + A
- Position Update:The updated velocity is then scaled by the delta time (D) to determine how far the particle will move in each frame:
- P = P + (V * D)
In this setup, any non-zero acceleration causes the particles to move. Acceleration in this context can be influenced by various factors such as collisions, external forces, or gravity.
Returning Particles to Their Original Positions
For this example, the goal is to bring each particle back to its initial position as accurately as possible (keeping in mind that particles may collide, so adjust your scene size accordingly). Here’s how:
- Capture the Starting Frame:The first frame of the animation is captured using the CacheTOP when you press the initialization button in the Flex solver. This frame serves as the baseline or "starting point" for all particles.
- Calculate the Return Vector:By subtracting the starting position from the current animated position, you obtain a vector that points toward the original location. This vector defines the velocity (V) needed to guide the particle back.
Balancing System Dynamics with MatteTOP
To avoid overly interfering with the natural dynamics once particles are released, balance is essential. This is where the MatteTOP comes into play—a powerful operator from computer graphics that blends multiple inputs. The MatteTOP accepts three inputs:
- Start
- End
- Weights (Bias)
The weights are provided as a black-and-white texture, which blends the inputs on a per-pixel basis (similar to the GLSL function mix(a, b, c)). This blending controls how strongly the return force is applied.
I use the spherical effector as the weights(Pallette/pointcloud/pointweights), which lets me target the exact areas of the point cloud that the matte affects, adding a fun and intuitive layer of control. (This is the actual 3rd input of the matteTOP)
By balancing acceleration, velocity, and position—and creatively employing the MatteTOP—you can make your point clouds come alive. This approach gives you full control over every particle while ensuring that their movement remains smooth, reversible, and true to your design
Experiment with these techniques and tweak the parameters to get exactly the behavior you’re looking for in your animation!
Happy flexing
