From e2fee30f901d11d0897655f032539b31758bbc1e Mon Sep 17 00:00:00 2001
From: Andinus <andinus@nand.sh>
Date: Sat, 9 Oct 2021 22:09:29 +0530
Subject: Add working DDA Algorithm

---
 public/global.css                      |  22 ++++++-
 src/algorithms/line-drawing/DDA.svelte | 108 ++++++++++++++++++++++++++-------
 2 files changed, 106 insertions(+), 24 deletions(-)

diff --git a/public/global.css b/public/global.css
index a7545c5..70859df 100644
--- a/public/global.css
+++ b/public/global.css
@@ -98,13 +98,31 @@ a:visited:hover, a:visited:focus {
   background-color: var(--cyan-subtle-bg);
 }
 
-form, input {
+form, input, button {
   color: var(--fg-main);
   background-color: var(--bg-main);
   margin: .25em;
   padding: .25em;
+
 }
 
-input {
+input, button {
   border: 2px solid var(--bg-alt);
 }
+
+code {
+    font-size: 1rem; /* code size should be same as body */
+    padding: 0 0.4ch;
+    color: var(--fg-special-calm);
+    background-color: var(--bg-alt);
+}
+
+table {
+    width: 100%;
+    margin-bottom: 1em;
+    border-collapse: collapse;
+}
+tbody tr:nth-child(odd) td, tbody tr:nth-child(odd) th {
+    background-color: var(--bg-dim);
+}
+td, th { padding: .25em .5em; border: 1px solid var(--bg-alt); }
diff --git a/src/algorithms/line-drawing/DDA.svelte b/src/algorithms/line-drawing/DDA.svelte
index db2070a..b2cc558 100644
--- a/src/algorithms/line-drawing/DDA.svelte
+++ b/src/algorithms/line-drawing/DDA.svelte
@@ -1,12 +1,47 @@
 <script>
+  let solved = false;
+
   let x0 = 0, y0 = 0, x1 = 4, y1 = 4;
+  let dx, dy;
+
+  let steps;
+  let x_inc, y_inc;
+
+  let x_axis = [], y_axis = [];
+  let x_axis_floored = [], y_axis_floored = [];
+
+  function dda() {
+    dx = Math.abs(x1 - x0);
+    dy = Math.abs(y1 - y0);
+
+    steps = Math.max(...[dx, dy].map(x => Math.abs(x)));
+
+    x_inc = dx / steps;
+    y_inc = dy / steps;
+
+    // Build the x axis.
+    x_axis = [];
+    let X = x0;
+    for (let idx = 0; idx < steps; idx++) {
+      X += x_inc;
+      x_axis.push(X.toPrecision(3));
+    }
+    x_axis_floored = x_axis.map(function(x) {return Math.round(x)});
+
+    // Build the y axis.
+    y_axis = [];
+    let Y = y0;
+    for (let idx = 0; idx < steps; idx++) {
+      Y += y_inc;
+      y_axis.push(Y.toPrecision(3));
+    }
+    y_axis_floored = y_axis.map(function(y) {return Math.round(y)});
 
-  $: dx = x1 - x0;
-  $: dy = y1 - y0;
+    solved = true;
+  }
 
-  $: steps = Math.max(...[dx, dy].map(x => Math.abs(x)));
-  $: x_inc = dx / steps;
-  $: y_inc = dy / steps;
+  // Solve with prefilled values.
+  dda();
 </script>
 
 <h2>Digital differential analyzer</h2>
@@ -20,24 +55,53 @@
   <input type="number" id="x1" name="x1" bind:value={x1}>&nbsp;
   <label for="y1">y1: </label>
   <input type="number" id="y1" name="y1" bind:value={y1}>
+  <br>
+  <button type="button" on:click={dda}>Solve</button>
 </form>
-<hr>
-
-<label for="dx">dx: </label>
-<input type="text" id="dx" name="dx" value={dx} disabled><br>
-<label for="dy">dy: </label>
-<input type="text" id="dy" name="dy" value={dy} disabled>
-<hr>
-
-<label for="steps">steps: </label>
-<input type="text" id="steps" name="steps" value={steps} disabled>
-<hr>
-
-<label for="x_inc">x Increment: </label>
-<input type="text" id="x_inc" name="x_inc" value={x_inc} disabled><br>
-<label for="y_inc">y Increment: </label>
-<input type="text" id="y_inc" name="y_inc" value={y_inc} disabled>
-<hr>
+
+{#if solved === true && steps > 0}
+  <hr>
+  <label for="dx">dx = <code>|x1 - x0|</code>: </label>
+  <input type="text" id="dx" name="dx" value={dx} disabled><br>
+  <label for="dy">dy = <code>|y1 - y0|</code>: </label>
+  <input type="text" id="dy" name="dy" value={dy} disabled>
+  <hr>
+
+  <label for="steps">steps: </label>
+  <input type="text" id="steps" name="steps" value={steps} disabled>
+  <hr>
+
+  <label for="x_inc">x Increment = <code>dx / steps</code>: </label>
+  <input type="text" id="x_inc" name="x_inc" value={x_inc} disabled><br>
+  <label for="y_inc">y Increment = <code>dy / steps</code>: </label>
+  <input type="text" id="y_inc" name="y_inc" value={y_inc} disabled>
+  <hr>
+
+  <table>
+    <thead>
+      <tr>
+        <th>Iteration</th>
+        <th>x</th>
+        <th>y</th>
+        <th>x (plot)</th>
+        <th>y (plot)</th>
+      </tr>
+    </thead>
+
+    <tbody>
+      {#each x_axis as _, i}
+        <tr>
+          <td>{i + 1}</td>
+          <td>{x_axis[i]}</td>
+          <td>{y_axis[i]}</td>
+          <td>{x_axis_floored[i]}</td>
+          <td>{y_axis_floored[i]}</td>
+        </tr>
+      {/each}
+    </tbody>
+
+  </table>
+{/if}
 
 <style>
   hr { color: var(--bg-hl-alt-intense); }
-- 
cgit 1.4.1-2-gfad0