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36 lines
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<title>Math.inverse_lerp — Ludic</title>
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<meta name="description" content="Find where a value sits between two endpoints as a 0..1 fraction.">
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<header class="nav"><div class="wrap nav-in"><a class="brand" href="index.html"><span class="logo">L</span> Ludic</a><button class="nav-toggle" aria-label="Toggle menu" aria-expanded="false">☰</button><nav class="nav-links"><a href="index.html">Home</a><a href="api.html">API Reference</a><a class="nav-cta" href="https://git.workshopsoft.io/workshopsoft/ludic">Source ↗</a></nav></div></header>
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<div class="crumbs"><a href="api.html">API Reference</a> <span>›</span> <a href="ns-math.html">Math</a> <span>›</span> <span class="here">Math.inverse_lerp</span></div>
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<div class="item-head">
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<span class="kind-badge kind-method">method</span>
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<h1 id="top">Math.inverse_lerp</h1>
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<code class="sig">Math.inverse_lerp(a, b, v) -> fixed</code>
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<div class="desc"><p>The inverse of <code>Math.lerp</code>: given endpoints <code>a</code> and <code>b</code> and a value <code>v</code>, it returns the fraction <code>(v - a) / (b - a)</code> — <code>0.0</code> when <code>v</code> equals <code>a</code>, <code>1.0</code> when it equals <code>b</code>. Use it to turn a raw quantity into a normalized amount: how full a health bar is, how far a timer has run, or the <code>t</code> to feed into another <code>Math.lerp</code>. The endpoints must differ, since equal ones would divide by zero.</p></div>
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<div class="params"><h2>Parameters</h2><div class="param" id="param-a"><code class="pname">a</code><span class="pdesc">the endpoint that maps to <code>0.0</code></span></div><div class="param" id="param-b"><code class="pname">b</code><span class="pdesc">the endpoint that maps to <code>1.0</code></span></div><div class="param" id="param-v"><code class="pname">v</code><span class="pdesc">the value to locate between them</span></div></div>
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<div class="examples"><h2>Example</h2><pre data-lang="ludic">program HealthFraction {
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const MAX_HP: fixed = 200.0
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var hp: fixed = 150.0
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handler Draw phase Render {
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let fraction = Math.inverse_lerp(0.0, MAX_HP, hp) # 0.75
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}
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}</pre></div>
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