Building Worlds With Distance Functions in GLSL (Raymarching)

2013/05/24 JeGX

Article index:

3 – Raymarching: Floor + Sphere

Build Worlds With Distance Functions in GLSL, GLSL Hacker
Raymarching: floor + sphere

The new functions to generate this scene: obj_union() and obj_sphere():

vec2 obj_union(in vec2 obj0, in vec2 obj1)
{
  if (obj0.x < obj1.x)
  	return obj0;
  else
  	return obj1;
}

The obj_union() function will be used with all other primitives to combine the floor and a primitive. This function can be seen as the depth test.

Now the function to generate a sphere. This function returns the distance between a position p and a sphere with a radius of 1.9. The vec2 used to return the result holds the distance in x and the material index in y. If material == 0, we have the floor. If material == 1 we have a primitive.

vec2 obj_sphere(in vec3 p)
{
  float d = length(p)-1.9;
  return vec2(d,1);
}

Now let's see where to use both functions in our GLSL framework: we just need to modify the distance_to_obj() function like this:

vec2 distance_to_obj(in vec3 p)
{
  return obj_union(obj_floor(p), obj_sphere(p));
}

Article index:

Pages: 1 2 3 4 5 6 7 8 9

4 thoughts on “Building Worlds With Distance Functions in GLSL (Raymarching)”

GLSLnoob42 2013/12/23 at 10:46

Hey. Just found this. Came across iq’s stuff a while ago, but being a noob I couldn’t do anything with it.

Then while rediscovering GLSL & iq’s website, I found this awesome resource!

But here’s the thing, I can’t get it to work. ;o)

I eventually found 2 errors in the code. Here are the fixes:
line 97: d.x-distance_to_obj(p-e.yyx).x); // had an extra “)”
line 98: N = normalize(n); // was missing “;”

I’m trying to use GLSL Hacker 0.6.0.0 & Blender 2.69 using this tutorial:

http://en.wikibooks.org/wiki/GLSL_Programming/Blender/Minimal_Shader

Any help?

peace & 42