BFCM Globe 2023: Trig airplane movement

trig_airplanes.js

this.currentTime = { value: 0 };

airplaneMaterial.onBeforeCompile = (shader) =>; {
  shader.uniforms.uTime = this.currentTime;

  // Inject the uTime uniform into the shader
  shader.vertexShader = 'uniform float uTime;\n' + shader.vertexShader;

  // Modify the position calculations of the vertex shader to include our animation math
  shader.vertexShader = shader.vertexShader.replace(
    `#include <begin_vertex>;`,
    `
      vec3 transformed;
      float speed = 0.2;
      float radius = 1.0;

      float theta = uTime * speed;

      // Rotate each vertex around the origin
      transformed.x = position.x * cos(theta) - position.y * sin(theta);
      transformed.y = position.x * sin(theta) + position.y * cos(theta);
      transformed.z = position.z;

      // Offset each vertex by the radius
      transformed.x += cos(theta) * radius;
      transformed.y += sin(theta) * radius;
    `
  );
}