BabylonJS - 線段

線段是 3D 遊戲中的基本元素。要繪製線段，需要兩點才能在它們之間繪製線段。

演示

<!doctype html>
<html>
   <head>
      <meta charset = "utf-8">
      <title>BabylonJs - Basic Element-Creating Scene</title>
      <script src = "babylon.js"></script>
      <style>
         canvas {width: 100%; height: 100%;}
      </style>
   </head>

   <body>
      <canvas id = "renderCanvas"></canvas>
      <script type = "text/javascript">
         var canvas = document.getElementById("renderCanvas");
         var engine = new BABYLON.Engine(canvas, true);
         var createScene  = function() {
            var scene = new BABYLON.Scene(engine);
            scene.clearColor = new BABYLON.Color3( .5, .5, .5);
            
            var camera = new BABYLON.ArcRotateCamera("camera1",  0, 0, 0, new BABYLON.Vector3(0, 0, -0), scene);
            camera.setPosition(new BABYLON.Vector3(0, 0, -100));
            camera.attachControl(canvas, true);
            
            var light = new BABYLON.HemisphericLight("light1", new BABYLON.Vector3(1, 0.5, 0), scene);
            light.intensity = 0.7;
            
            var pl = new BABYLON.PointLight("pl", new BABYLON.Vector3(0, 0, 0), scene);
            pl.diffuse = new BABYLON.Color3(1, 1, 1);
            pl.specular = new BABYLON.Color3(1, 0, 0);
            pl.intensity = 0.95;


            // lines creation
            var path = [];
            for(var t = 0; t < 40; t++) {
               var x = t*Math.cos(5*t);
               var y = t*Math.sin(5*t);
               var z = 0;
               path.push(new BABYLON.Vector3(x, y, z));
            }
            
            var mesh = BABYLON.Mesh.CreateLines("lines", path, scene, true);

            var k = 0;
            scene.registerBeforeRender(function() {			
               pl.position = camera.position;
            });
            return scene; 
         };
         var scene = createScene();
         engine.runRenderLoop(function() {
            scene.render();
         });
      </script>
   </body>
</html>

輸出

以上程式碼行生成以下輸出 −

要獲取沿 x 和 y 軸的座標，請使用以下方程式（數學函式）並使用 x 和 y 值建立路徑。與 babylonjs 的 createline 類相同。使用您選擇的任意方程式，嘗試建立不同的線段。

var mesh = BABYLON.Mesh.CreateLines("lines", path, scene, true);

使用以下方程式建立線段 −

var x = t*Math.cos(5*t);
var y = t*Math.sin(5*t);
var z = 0;

t 的值從 0 到 40。

執行以下程式碼行時，形狀會發生變化 −

var x = t * Math.cos(6 * t);
var y = t * Math.sin(6 * t);
var z = 0;

線段的形狀如下所示 −

babylonjs_parametric_shapes.htm

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