//go:build ignore

//kage:unit pixels

package main

var Time float

func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
	orig := imageSrc0At(srcPos)
	if orig.a < 0.01 {
		return orig
	}


	limit := min(Time/0.5, 2.0)
	level := imageSrc3UnsafeAt(srcPos).x

	// Burning effect: brighten core, add orange-red glow on edges
	
	burnWidth := 0.15
	borderLow := limit - burnWidth
	borderHigh := limit

	// Inner burned area: dark (char), outer edge: bright fire colors
	if level < borderLow {
		return vec4(0.05, 0.02, 0.0, 1.0) // black char
	} else if level < borderHigh {
		t := (level - borderLow) / (borderHigh - borderLow)
		// Orange to yellow
		r := 1.0
		g := 0.4 + t*0.6
		b := 0.0 + t*0.2
		return vec4(r, g, b, 1.0)
	} else if level < limit + 0.3 {
		t := (level - borderHigh) / 0.3
		// Glow fades out
		r := 1.0 * (1.0 - t)
		g := (0.8) * (1.0 - t*t)
		b := (0.3) * (1.0 - t*t*t)
		return vec4(r, g, b, 1.0)
	}

	return imageSrc0UnsafeAt(srcPos)
}