GiovannyJTT / exploding_bunny

Basic OpenGL app that shows the explosion effect of an object using C++ and GLSL geometry shader.

Exploding Bunny

OpenGL app that shows the explosion effect of an object using C++ and GLSL. Most of the computations are performed in the geometry shader. It uses the parametric coordinates of the triangles for subdividing them N times and translate the new produced vertices over time. It uses the centroid of the triangles as reference for the direction vectors of traslation for each new vertex.

Video Demo Link https://youtu.be/FPhnLEm4NMk

GLSL Program Description

General description of the code. You can find also comments in all shader files.

• Steps performed for getting the explosion effect
  • Set V0 as original position of vertices[0] of the triangle
  • Set V01 and V02 as vectors on the triangle plane (from vertices[0] to vertices[1] and vertices[2] respectively)
  • Compute normal vector of the triangle as vector product between V01 and V02
  • Compute centroid of triangle
  • Set number of layers as numLayers = 2 ^ uLevel, where uLevel is number of times for repeating the subdivision
  • Set deltas of displacement (dt and ds) for the parametric coordinates of the triangle (s and t)
  • For each subdivision
    • Call produceVertex passing parametric coordinates values depending on the subdivision
      • Coordinates of new vertex will computed as vec3 v = V0 + s*V01 + t*V02
    • Example of parametric coordinates:
      • 
    • Set direction vector for displacing every new vertex using the triangle centroid as origin reference
    • Compute the final position of the new vertex taking into account the translation units uT and the velocity factor vel
    • (Optional) Clipping vertices against a cube
      • All vertices inside the cube will be removed (not sent to fragment shader)
        • It uses the angles among auxiliar vectors (from the center of every cube-side to the vertex) and the cube-side normals.
        • The vertex will be considered inside the cube when all cos are <= 0
        • The clipped vertices will be rendered with red color