Added optional alphaFilter parameter to CreateGroundFromHeightMap to allow for heightmaps to be created that ignore any transparent data

src/Mesh/babylon.mesh.ts

@@ -3136,6 +3136,7 @@
          * The parameter `minHeight` (float, default 0) is the minimum altitude on the ground.     
          * The parameter `maxHeight` (float, default 1) is the maximum altitude on the ground.   
          * The parameter `onReady` is a javascript callback function that will be called  once the mesh is just built (the height map download can last some time).  
+         * The parameter `alphaFilter` will filter any data where the alpha channel is below this value, defaults 0 (all data visible)
          * This function is passed the newly built mesh : 
          * ```javascript
          * function(mesh) { // do things
@@ -3143,7 +3144,7 @@
          * ```
          * 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 CreateGroundFromHeightMap(name: string, url: string, width: number, height: number, subdivisions: number, minHeight: number, maxHeight: number, scene: Scene, updatable?: boolean, onReady?: (mesh: GroundMesh) => void): GroundMesh {
+        public static CreateGroundFromHeightMap(name: string, url: string, width: number, height: number, subdivisions: number, minHeight: number, maxHeight: number, scene: Scene, updatable?: boolean, onReady?: (mesh: GroundMesh) => void, alphaFilter?: number): GroundMesh {
             var options = {
                 width: width,
                 height: height,
@@ -3151,7 +3152,8 @@
                 minHeight: minHeight,
                 maxHeight: maxHeight,
                 updatable: updatable,
-                onReady: onReady
+                onReady: onReady,
+                alphaFilter: alphaFilter
             };
 
             return MeshBuilder.CreateGroundFromHeightMap(name, url, options, scene);

src/Mesh/babylon.mesh.vertexData.ts

@@ -1739,15 +1739,17 @@
           * * buffer the array holding the image color data 
           * * bufferWidth the width of image
           * * bufferHeight the height of image
+          * * alphaFilter Remove any data where the alpha channel is below this value, defaults 0 (all data visible)
          * @returns the VertexData of the Ground designed from a heightmap   
          */
-        public static CreateGroundFromHeightMap(options: { width: number, height: number, subdivisions: number, minHeight: number, maxHeight: number, colorFilter: Color3, buffer: Uint8Array, bufferWidth: number, bufferHeight: number }): VertexData {
+        public static CreateGroundFromHeightMap(options: { width: number, height: number, subdivisions: number, minHeight: number, maxHeight: number, colorFilter: Color3, buffer: Uint8Array, bufferWidth: number, bufferHeight: number, alphaFilter: number }): VertexData {
             var indices = [];
             var positions = [];
             var normals = [];
             var uvs = [];
             var row, col;
             var filter = options.colorFilter || new Color3(0.3, 0.59, 0.11);
+            var alphaFilter = options.alphaFilter || 0.0;
 
             // Vertices
             for (row = 0; row <= options.subdivisions; row++) {
@@ -1762,10 +1764,17 @@
                     var r = options.buffer[pos] / 255.0;
                     var g = options.buffer[pos + 1] / 255.0;
                     var b = options.buffer[pos + 2] / 255.0;
+                    var a = options.buffer[pos + 3] / 255.0;
 
                     var gradient = r * filter.r + g * filter.g + b * filter.b;
-
-                    position.y = options.minHeight + (options.maxHeight - options.minHeight) * gradient;
+                    
+                    // If our alpha channel is not within our filter then we will assign a 'special' height 
+                    // Then when building the indicies, we will ignore any vertex that is using the special height
+                    if(a >= alphaFilter)
+                        position.y = options.minHeight + (options.maxHeight - options.minHeight) * gradient;
+                    else {
+                        position.y = options.minHeight - 1; // We can't have a height below minHeight, normally.
+                    }
 
                     // Add  vertex
                     positions.push(position.x, position.y, position.z);
@@ -1777,13 +1786,33 @@
             // Indices
             for (row = 0; row < options.subdivisions; row++) {
                 for (col = 0; col < options.subdivisions; col++) {
-                    indices.push(col + 1 + (row + 1) * (options.subdivisions + 1));
-                    indices.push(col + 1 + row * (options.subdivisions + 1));
-                    indices.push(col + row * (options.subdivisions + 1));
+                    // Calculate indcies
+                    var idx1 = (col + 1 + (row + 1) * (options.subdivisions + 1));
+                    var idx2 = (col + 1 + row * (options.subdivisions + 1));
+                    var idx3 = (col + row * (options.subdivisions + 1));
+                    var idx4 = (col + (row + 1) * (options.subdivisions + 1));
+                    var idx5 = (col + 1 + (row + 1) * (options.subdivisions + 1));
+                    var idx6 = (col + row * (options.subdivisions + 1));
+
+                    // Check that all indicies are visible (based on our special height)
+                    // Only display the vertex if all indcies are visible
+                    var isVisibleIdx1 = positions[idx1 * 3 + 1] >= options.minHeight;
+                    var isVisibleIdx2 = positions[idx2 * 3 + 1] >= options.minHeight;
+                    var isVisibleIdx3 = positions[idx3 * 3 + 1] >= options.minHeight;
+                    if (isVisibleIdx1 && isVisibleIdx2 && isVisibleIdx3) {
+                        indices.push(idx1);
+                        indices.push(idx2);
+                        indices.push(idx3);
+                    }
 
-                    indices.push(col + (row + 1) * (options.subdivisions + 1));
-                    indices.push(col + 1 + (row + 1) * (options.subdivisions + 1));
-                    indices.push(col + row * (options.subdivisions + 1));
+                    var isVisibleIdx4 = positions[idx4 * 3 + 1] >= options.minHeight;
+                    var isVisibleIdx5 = positions[idx5 * 3 + 1] >= options.minHeight;
+                    var isVisibleIdx6 = positions[idx6 * 3 + 1] >= options.minHeight;
+                    if (isVisibleIdx4 && isVisibleIdx5 && isVisibleIdx6) {
+                        indices.push(idx4);
+                        indices.push(idx5);
+                        indices.push(idx6);
+                    }
                 }
             }
 

src/Mesh/babylon.meshBuilder.ts

@@ -776,6 +776,7 @@
          * * The parameter `maxHeight` (float, default 1) is the maximum altitude on the ground.   
          * * The parameter `colorFilter` (optional Color3, default (0.3, 0.59, 0.11) ) is the filter to apply to the image pixel colors to compute the height.  
          * * The parameter `onReady` is a javascript callback function that will be called  once the mesh is just built (the height map download can last some time).  
+         * * The parameter `alphaFilter` will filter any data where the alpha channel is below this value, defaults 0 (all data visible)
          * * The mesh can be set to updatable with the boolean parameter `updatable` (default false) if its internal geometry is supposed to change once created.  
          * @param name defines the name of the mesh
          * @param url defines the url to the height map
@@ -785,13 +786,14 @@
          * @see http://doc.babylonjs.com/babylon101/height_map   
          * @see http://doc.babylonjs.com/tutorials/Mesh_CreateXXX_Methods_With_Options_Parameter#ground-from-a-height-map
          */
-        public static CreateGroundFromHeightMap(name: string, url: string, options: { width?: number, height?: number, subdivisions?: number, minHeight?: number, maxHeight?: number, colorFilter?: Color3, updatable?: boolean, onReady?: (mesh: GroundMesh) => void }, scene: Scene): GroundMesh {
+        public static CreateGroundFromHeightMap(name: string, url: string, options: { width?: number, height?: number, subdivisions?: number, minHeight?: number, maxHeight?: number, colorFilter?: Color3, alphaFilter?: number, updatable?: boolean, onReady?: (mesh: GroundMesh) => void }, scene: Scene): GroundMesh {
             var width = options.width || 10.0;
             var height = options.height || 10.0;
             var subdivisions = options.subdivisions || 1 | 0;
             var minHeight = options.minHeight || 0.0;
             var maxHeight = options.maxHeight || 1.0;
             var filter = options.colorFilter || new Color3(0.3, 0.59, 0.11);
+            var alphaFilter = options.alphaFilter || 0.0;
             var updatable = options.updatable;
             var onReady = options.onReady;
 
@@ -834,7 +836,8 @@
                     width: width, height: height,
                     subdivisions: subdivisions,
                     minHeight: minHeight, maxHeight: maxHeight, colorFilter: filter,
-                    buffer: buffer, bufferWidth: bufferWidth, bufferHeight: bufferHeight
+                    buffer: buffer, bufferWidth: bufferWidth, bufferHeight: bufferHeight, 
+                    alphaFilter: alphaFilter
                 });
 
                 vertexData.applyToMesh(ground, updatable);

what's new.md

@@ -122,6 +122,7 @@
 - New `serialize` and `Parse` functions for SSAO2 Rendering Pipeline ([julien-moreau](https://github.com/julien-moreau))
 - Added `furOcclusion` property to FurMaterial to control the occlusion strength ([julien-moreau](https://github.com/julien-moreau))
 - Optimize ephimeral object creation to help GC ([menduz](https://github.com/menduz))
+- Added optional alphaFilter parameter to ```CreateGroundFromHeightMap``` to allow for heightmaps to be created that ignore any transparent data ([Postman-nz](https://github.com/Postman-nz))
 
 ## Bug fixes