optional use of vertex alpha

src/Mesh/babylon.linesMesh.ts

@@ -32,13 +32,14 @@
         private _intersectionThreshold: number;
         private _colorShader: ShaderMaterial;
 
-        constructor(name: string, scene: Nullable<Scene> = null, parent: Nullable<Node> = null, source?: LinesMesh, doNotCloneChildren?: boolean, public useVertexColor?: boolean) {
+        constructor(name: string, scene: Nullable<Scene> = null, parent: Nullable<Node> = null, source?: LinesMesh, doNotCloneChildren?: boolean, public useVertexColor?: boolean, public useVertexAlpha?: boolean) {
             super(name, scene, parent, source, doNotCloneChildren);
 
             if (source) {
                 this.color = source.color.clone();
                 this.alpha = source.alpha;
                 this.useVertexColor = source.useVertexColor;
+                this.useVertexAlpha = source.useVertexAlpha;
             }
 
             this._intersectionThreshold = 0.1;
@@ -47,7 +48,7 @@
             var options = {
                 attributes: [VertexBuffer.PositionKind],
                 uniforms: ["world", "viewProjection"],
-                needAlphaBlending: true,
+                needAlphaBlending: false,
                 defines: defines
             };
             
@@ -55,6 +56,7 @@
                 options.uniforms.push("color");
             }
             else {
+                options.needAlphaBlending = (useVertexAlpha) ? true : false;
                 options.defines.push("#define VERTEXCOLOR");
                 options.attributes.push(VertexBuffer.ColorKind);
             }

src/Mesh/babylon.meshBuilder.ts

@@ -359,11 +359,12 @@
          * The parameter `lines` is an array of lines, each line being an array of successive Vector3.   
          * The optional parameter `instance` is an instance of an existing LineSystem object to be updated with the passed `lines` parameter. The way to update it is the same than for 
          * The optional parameter `colors` is an array of line colors, each line colors being an array of successive Color4, one per line point.  
+         * The optional parameter `useVertexAlpha' is to be set to `true` (default `false`) when the alpha value from the former `Color4` array must be used.  
          * updating a simple Line mesh, you just need to update every line in the `lines` array : http://doc.babylonjs.com/tutorials/How_to_dynamically_morph_a_mesh#lines-and-dashedlines   
          * When updating an instance, remember that only line point positions can change, not the number of points, neither the number of lines.      
          * The mesh can be set to updatable with the boolean parameter `updatable` (default false) if its internal geometry is supposed to change once created.  
          */
-        public static CreateLineSystem(name: string, options: { lines: Vector3[][], updatable: boolean, instance: Nullable<LinesMesh>, colors?: Nullable<Color4[][]> }, scene: Nullable<Scene>): LinesMesh {
+        public static CreateLineSystem(name: string, options: { lines: Vector3[][], updatable: boolean, instance: Nullable<LinesMesh>, colors?: Nullable<Color4[][]>, useVertexAlpha?: boolean }, scene: Nullable<Scene>): LinesMesh {
             var instance = options.instance;
             var lines = options.lines;
             var colors = options.colors;
@@ -403,7 +404,7 @@
 
             // line system creation
             var useVertexColor = (colors) ? true : false;
-            var lineSystem = new LinesMesh(name, scene, null, undefined, undefined, useVertexColor);
+            var lineSystem = new LinesMesh(name, scene, null, undefined, undefined, useVertexColor, options.useVertexAlpha);
             var vertexData = VertexData.CreateLineSystem(options);
             vertexData.applyToMesh(lineSystem, options.updatable);
             return lineSystem;
@@ -417,12 +418,13 @@
          * The parameter `points` is an array successive Vector3.   
          * The optional parameter `instance` is an instance of an existing LineMesh object to be updated with the passed `points` parameter : http://doc.babylonjs.com/tutorials/How_to_dynamically_morph_a_mesh#lines-and-dashedlines    
          * The optional parameter `colors` is an array of successive Color4, one per line point.  
+         * The optional parameter `useVertexAlpha' is to be set to `true` (default `false`) when the alpha value from the former `Color4` array must be used.  
          * When updating an instance, remember that only point positions can change, not the number of points.      
          * The mesh can be set to updatable with the boolean parameter `updatable` (default false) if its internal geometry is supposed to change once created.  
          */
-        public static CreateLines(name: string, options: { points: Vector3[], updatable: boolean, instance: Nullable<LinesMesh>, colors?: Color4[] }, scene: Nullable<Scene> = null): LinesMesh {
+        public static CreateLines(name: string, options: { points: Vector3[], updatable: boolean, instance: Nullable<LinesMesh>, colors?: Color4[], useVertexAlpha?: boolean }, scene: Nullable<Scene> = null): LinesMesh {
             var colors = (options.colors) ? [options.colors] : null;
-            var lines = MeshBuilder.CreateLineSystem(name, { lines: [options.points], updatable: options.updatable, instance: options.instance, colors: colors }, scene);
+            var lines = MeshBuilder.CreateLineSystem(name, { lines: [options.points], updatable: options.updatable, instance: options.instance, colors: colors, useVertexAlpha: options.useVertexAlpha }, scene);
             return lines;
         }