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smooth godray transition

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koehr 2018-05-17 01:39:41 +02:00
parent faa605e836
commit 2764d3c52b
1 changed files with 11 additions and 13 deletions
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24
src/solar-quartet.js
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@ -31,15 +31,13 @@ export default function drawFrame (canvas, ctx, width, height, grCanvas, grCtx,
// If you're not space-bound you can add another stop or two, maybe fade out to black,
// but this actually looks good enough.
// we use different gradients for different day times (sunY):
// > -25: night (black sky)
// < -70: day (blue sky)
// otherwise red (dawn / sunset)
// a black "gradient" means no emission, so we fade to black as transition to night or day
let emissionStrength = 1.0
if (sunY > -30) emissionStrength -= Math.max((30 + sunY) / 5, 0.0)
else if (sunY < -60) emissionStrength += Math.min(1 + (60 + sunY) / 5, 0.0)
if (sunY < -25 && sunY > -70) { // dawn or sunset
emissionGradient.addColorStop(.1, '#0C0804') // pixels in radius 0 to 4.4 (44 * .1).
emissionGradient.addColorStop(.2, '#060201') // everything past radius 8.8.
}
emissionGradient.addColorStop(.1, `hsl(30,50%,${3.1 * emissionStrength}%)`) // pixels in radius 0 to 4.4 (44 * .1).
emissionGradient.addColorStop(.2, `hsl(12,71%,${1.4 * emissionStrength}%)`) // pixels in radius 0 to 4.4 (44 * .1).
// Now paint the gradient all over our godrays canvas.
grCtx.fillRect(0, 0, grWidth, grHeight)
@ -49,19 +47,19 @@ export default function drawFrame (canvas, ctx, width, height, grCanvas, grCtx,
// Paint the sky
const skyGradient = ctx.createLinearGradient(0, 0, 0, height)
// hue from blue to red depending on the suns position
const skyHue = 360 + sunY
// lesser saturation at day so that the red fades away
const skySaturation = 100 + sunY
// darker at night
const skyLightness = Math.min(sunY * -1 - 10, 55)
const skyHSLTop = `hsl(220, 70%, ${skyLightness}%)`
const skyHSLBottom = `hsl(${skyHue}, ${skySaturation}%, ${skyLightness}%)`
skyGradient.addColorStop(0, skyHSLTop)
skyGradient.addColorStop(.7, skyHSLBottom)
/*
skyGradient.addColorStop(0, '#2a3e55') // Blueish at the top.
skyGradient.addColorStop(.7, '#8d4835') // Reddish at the bottom.
}
*/
ctx.fillStyle = skyGradient
ctx.fillRect(0, 0, width, height)