superShapeSDF: Parametric Superformula Distance Field

Gielis Superformula for Organic Shape Generation

The superShapeSDF function implements the Gielis superformula, a mathematical equation capable of generating a wide variety of natural and geometric shapes through parametric control. This function creates complex organic forms ranging from flowers to starfish through precise mathematical parametrization.

Mathematical Foundation

The superformula is defined in polar coordinates:

$$r(\theta) = \left[ \left| \frac{1}{a} \cos\left(\frac{m\theta}{4}\right) \right|^{n_2} + \left| \frac{1}{b} \sin\left(\frac{m\theta}{4}\right) \right|^{n_3} \right]^{-1/n_1}$$

The distance calculation converts the point to polar coordinates, computes the superformula radius, and measures deviation:

$$d = |p| \cdot 5 - |s \cdot r(\theta) \cdot (\cos\theta, \sin\theta)|$$

Function Signatures

superShapeSDF

Parameter	Type	Description
st	vec2	Sample point position
s	float	Overall scale factor
a	float	X-axis scaling parameter
b	float	Y-axis scaling parameter
n1	float	Primary shape exponent
n2	float	Cosine term exponent
n3	float	Sine term exponent
m	float	Rotational symmetry order

superShapeSDFCenter

Same parameters as superShapeSDF plus:

Parameter	Type	Description
center	vec2	Shape center position

Parameter Effects

Parameter	Range	Effect
m	1-20	Rotational symmetry (m=4 creates 4-fold symmetry)
n1	0.1-10	Overall shape roundness/sharpness
n2, n3	0.1-10	Cosine/sine term sharpness
a, b	0.1-2	Axis scaling ratios

Implementation Demonstrations

ライブエディター

const fragment = () => {
      const p = uv.mul(2).sub(1).mul(0.1)
      const dist = superShapeSDFCenter(p, vec2(0), 0.5, 1, 1, 1, 1, 1, 5)
      const color = float(0).step(dist).oneMinus()
      return vec4(vec3(color), 1)
}