blendGlow: Luminous Light Emission

Mathematical Foundation of Glow

Glow blending is mathematically identical to reflect blending but with reversed parameter order: blendReflect(blend, base). This reversal creates luminous lighting effects where the blend layer acts as a light source illuminating the base layer.

The mathematical definition is:

$$C_{glow} = \text{blendReflect}(C_{blend}, C_{base}) = \begin{cases} 1 & \text{if } C_{base} = 1 \\ \min\left(\frac{C_{blend}^2}{1 - C_{base}}, 1\right) & \text{otherwise} \end{cases}$$

This parameter reversal transforms the mathematical behavior, making bright blend values create intense glow effects on the base layer.

Luminous Emission Properties

Property	Description	Visual Effect
Parameter Reversal	Blend and base roles swapped	Different lighting behavior
Light Source Effect	Bright blend creates glow	Luminous emanation
Intensity Amplification	Non-linear brightness boost	Dramatic lighting
Selective Illumination	Darker areas remain unaffected	Natural light falloff

ライブエディター

const fragment = () => {
      const base = vec3(0.05, 0.05, 0.1)
      const center = vec2(0.5)
      const dist = uv.sub(center).length()
      const hotSpot = float(0.5).smoothstep(0.05, dist)
      const warmGlow = vec3(1.0, 0.8, 0.3).mul(hotSpot)
      const result = blendGlowVec3(base, warmGlow)
      return vec4(result, 1)
}

結果

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