Code available here: https://github.com/mollikka/LedChristmas
A Christmas tree is decorated with an addressable RGB led strip. The coordinates of the lights are calculated using 2 cameras. Each year during Christmas holidays I tinker with this festive low resolution screen to display new 3D visuals.
Video samples
void coolball_presentation(int led, unsigned long time) {
const int centerx = 50;
const int centery = 50;
const int centerz = 70;
int x = XCOORD[led];
int y = YCOORD[led];
int z = ZCOORD[led];
float ballx = sin(float(time)/1000)*50 + centerx;
float bally = cos(float(time)/600)*50 + centery;
float ballz = sin(float(time)/760)*50 + centerz;
float distancesq = pow(ballx-x, 2) + pow(bally-y, 2) + pow(ballz-z, 2);
leds[led] = CHSV(max(0,200-0.2*distancesq),200,max(0,200-0.05*distancesq));
}