Generate mesh

This page describes how to dynamically generate mesh object at runtime using a trait script.

Setup a simple scene with single plane in the center. Assign default material and create a static rigid body for the plane.

Now we can start writing a trait that will dynamically generate a mesh and spawn it in the scene. For this example Haxe is used.

Select Camera and attach a new trait using Object tab - Armory Traits - +. Hit New Script and name it BoxGenerator.

Pressing Edit Script will open our new trait script in Kode Studio. Example code below will generate a simple box, attach a rigid body trait and spawn it on the plane after pressing input.

package arm;

import armory.Scene;
import armory.data.SceneFormat;
import armory.data.Data;
import armory.data.MeshData;
import armory.data.MaterialData;
import armory.system.Input;

@:keep
class BoxGenerator extends armory.Trait {

    var meshData:MeshData;
    var materials:haxe.ds.Vector<MaterialData>;

    function toF32(ar:Array<Float>):kha.arrays.Float32Array {
        var vals = new kha.arrays.Float32Array(ar.length);
        for (i in 0...vals.length) vals[i] = ar[i];
        return vals;
    }

    function toU32(ar:Array<Int>):kha.arrays.Uint32Array {
        var vals = new kha.arrays.Uint32Array(ar.length);
        for (i in 0...vals.length) vals[i] = ar[i];
        return vals;
    }

    public function new() {
        super();

        var pos:TVertexArray = {
            attrib: "pos",
            size: 3,
            values: toF32([1.0,1.0,-1.0,1.0,-1.0,-1.0,-1.0,-1.0,-1.0,-1.0,1.0,-1.0,1.0,1.0,1.0,-1.0,1.0,1.0,-1.0,-1.0,1.0,1.0,-1.0,1.0,1.0,1.0,-1.0,1.0,1.0,1.0,1.0,-1.0,1.0,1.0,-1.0,-1.0,1.0,-1.0,-1.0,1.0,-1.0,1.0,-1.0,-1.0,1.0,-1.0,-1.0,-1.0,-1.0,-1.0,-1.0,-1.0,-1.0,1.0,-1.0,1.0,1.0,-1.0,1.0,-1.0,1.0,1.0,1.0,1.0,1.0,-1.0,-1.0,1.0,-1.0,-1.0,1.0,1.0])
        };

        var nor:TVertexArray = {
            attrib: "nor",
            size: 3,
            values: toF32([0.0,0.0,-1.0,0.0,0.0,-1.0,0.0,0.0,-1.0,0.0,0.0,-1.0,0.0,0.0,1.0,0.0,0.0,1.0,0.0,0.0,1.0,0.0,0.0,1.0,1.0,0.0,0.0,1.0,0.0,0.0,1.0,0.0,0.0,1.0,0.0,0.0,0.0,-1.0,-0.0,0.0,-1.0,-0.0,0.0,-1.0,-0.0,0.0,-1.0,-0.0,-1.0,0.0,-0.0,-1.0,0.0,-0.0,-1.0,0.0,-0.0,-1.0,0.0,-0.0,0.0,1.0,0.0,0.0,1.0,0.0,0.0,1.0,0.0,0.0,1.0,0.0])
        };

        var indices:TIndexArray = {
            material: 0,
            size: 3,
            values: toU32[0,1,2,0,2,3,4,5,6,4,6,7,8,9,10,8,10,11,12,13,14,12,14,15,16,17,18,16,18,19,20,21,22,20,22,23])
        };

        var rawmesh:TMesh = {
            vertex_arrays: [pos, nor],
            index_arrays: [indices]
        };

        var rawmeshData:TMeshData = { 
            name: "BoxMesh",
            mesh: rawmesh 
        };

        new MeshData(rawmeshData, function(data:MeshData) {
            // Mesh data parsed
            meshData = data;
            meshData.mesh.calculateAABB();

            // Fetch material from scene data
            Data.getMaterial("Scene", "Material", function(data:MaterialData) {
                // Material loaded
                materials = haxe.ds.Vector.fromData([data]);
                notifyOnUpdate(update);
            });
        });
    }

    function update() {
        // Left mouse button was pressed / display touched / ..
        if (Input.started) {
            // Create new object in active scene
            var object = Scene.active.addMeshObject(meshData, materials);

            // Just for testing, add rigid body trait
            var aabb = meshData.mesh.aabb;
            object.transform.setDimensions(aabb.x, aabb.y, aabb.z);
            object.transform.set(Math.random() * 8 - 4, Math.random() * 8 - 4, 5);
            object.addTrait(new armory.trait.internal.RigidBody());
        }
    }
}

Hit Play in Viewport to verity results!

Get the blend file at GitHub.

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