GLTFLoader: Embedd toTrianglesDrawMode().

examples/js/loaders/GLTFLoader.js

@@ -2394,6 +2394,100 @@ THREE.GLTFLoader = ( function () {
 
 	}
 
+	/**
+	 * @param {THREE.BufferGeometry} geometry
+	 * @param {Number} drawMode
+	 * @return {THREE.BufferGeometry}
+	 */
+	function toTrianglesDrawMode( geometry, drawMode ) {
+
+		var index = geometry.getIndex();
+
+		// generate index if not present
+
+		if ( index === null ) {
+
+			var indices = [];
+
+			var position = geometry.getAttribute( 'position' );
+
+			if ( position !== undefined ) {
+
+				for ( var i = 0; i < position.count; i ++ ) {
+
+					indices.push( i );
+
+				}
+
+				geometry.setIndex( indices );
+				index = geometry.getIndex();
+
+			} else {
+
+				console.error( 'THREE.GLTFLoader.toTrianglesDrawMode(): Undefined position attribute. Processing not possible.' );
+				return geometry;
+
+			}
+
+		}
+
+		//
+
+		var numberOfTriangles = index.count - 2;
+		var newIndices = [];
+
+		if ( drawMode === THREE.TriangleFanDrawMode ) {
+
+			// gl.TRIANGLE_FAN
+
+			for ( var i = 1; i <= numberOfTriangles; i ++ ) {
+
+				newIndices.push( index.getX( 0 ) );
+				newIndices.push( index.getX( i ) );
+				newIndices.push( index.getX( i + 1 ) );
+
+			}
+
+		} else {
+
+			// gl.TRIANGLE_STRIP
+
+			for ( var i = 0; i < numberOfTriangles; i ++ ) {
+
+				if ( i % 2 === 0 ) {
+
+					newIndices.push( index.getX( i ) );
+					newIndices.push( index.getX( i + 1 ) );
+					newIndices.push( index.getX( i + 2 ) );
+
+
+				} else {
+
+					newIndices.push( index.getX( i + 2 ) );
+					newIndices.push( index.getX( i + 1 ) );
+					newIndices.push( index.getX( i ) );
+
+				}
+
+			}
+
+		}
+
+		if ( ( newIndices.length / 3 ) !== numberOfTriangles ) {
+
+			console.error( 'THREE.GLTFLoader.toTrianglesDrawMode(): Unable to generate correct amount of triangles.' );
+
+		}
+
+		// build final geometry
+
+		var newGeometry = geometry.clone();
+		newGeometry.setIndex( newIndices );
+
+		return newGeometry;
+
+	}
+
 	/**
 	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
 	 *
@@ -2524,9 +2618,13 @@ THREE.GLTFLoader = ( function () {
 
 						}
 
-						if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP || primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ) {
+						if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ) {
+
+							mesh.geometry = toTrianglesDrawMode( mesh.geometry, THREE.TriangleStripDrawMode );
+
+						} else if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ) {
 
-							console.warn( 'THREE.GLTFLoader: The draw modes triangle strip and fan are not supported anymore.' );
+							mesh.geometry = toTrianglesDrawMode( mesh.geometry, THREE.TriangleFanDrawMode );
 
 						}
 

examples/jsm/loaders/GLTFLoader.js

@@ -63,6 +63,8 @@ import {
 	Sphere,
 	SpotLight,
 	TextureLoader,
+	TriangleFanDrawMode,
+	TriangleStripDrawMode,
 	UniformsUtils,
 	Vector2,
 	Vector3,
@@ -2459,6 +2461,101 @@ var GLTFLoader = ( function () {
 
 	}
 
+	/**
+	 * @param {BufferGeometry} geometry
+	 * @param {Number} drawMode
+	 * @return {BufferGeometry}
+	 */
+	function toTrianglesDrawMode( geometry, drawMode ) {
+
+		var index = geometry.getIndex();
+
+		// generate index if not present
+
+		if ( index === null ) {
+
+			var indices = [];
+
+			var position = geometry.getAttribute( 'position' );
+
+			if ( position !== undefined ) {
+
+				for ( var i = 0; i < position.count; i ++ ) {
+
+					indices.push( i );
+
+				}
+
+				geometry.setIndex( indices );
+				index = geometry.getIndex();
+
+			} else {
+
+				console.error( 'THREE.GLTFLoader.toTrianglesDrawMode(): Undefined position attribute. Processing not possible.' );
+				return geometry;
+
+			}
+
+		}
+
+		//
+
+		var numberOfTriangles = index.count - 2;
+		var newIndices = [];
+
+		if ( drawMode === TriangleFanDrawMode ) {
+
+			// gl.TRIANGLE_FAN
+
+			for ( var i = 1; i <= numberOfTriangles; i ++ ) {
+
+				newIndices.push( index.getX( 0 ) );
+				newIndices.push( index.getX( i ) );
+				newIndices.push( index.getX( i + 1 ) );
+
+			}
+
+		} else {
+
+			// gl.TRIANGLE_STRIP
+
+			for ( var i = 0; i < numberOfTriangles; i ++ ) {
+
+				if ( i % 2 === 0 ) {
+
+					newIndices.push( index.getX( i ) );
+					newIndices.push( index.getX( i + 1 ) );
+					newIndices.push( index.getX( i + 2 ) );
+
+
+				} else {
+
+					newIndices.push( index.getX( i + 2 ) );
+					newIndices.push( index.getX( i + 1 ) );
+					newIndices.push( index.getX( i ) );
+
+				}
+
+			}
+
+		}
+
+		if ( ( newIndices.length / 3 ) !== numberOfTriangles ) {
+
+			console.error( 'THREE.GLTFLoader.toTrianglesDrawMode(): Unable to generate correct amount of triangles.' );
+
+		}
+
+		// build final geometry
+
+		var newGeometry = geometry.clone();
+		newGeometry.setIndex( newIndices );
+		newGeometry.clearGroups();
+
+		return newGeometry;
+
+	}
+
 	/**
 	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
 	 *
@@ -2589,9 +2686,13 @@ var GLTFLoader = ( function () {
 
 						}
 
-						if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP || primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ) {
+						if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ) {
+
+							mesh.geometry = toTrianglesDrawMode( mesh.geometry, TriangleStripDrawMode );
+
+						} else if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ) {
 
-							console.warn( 'THREE.GLTFLoader: The draw modes triangle strip and fan are not supported anymore.' );
+							mesh.geometry = toTrianglesDrawMode( mesh.geometry, TriangleFanDrawMode );
 
 						}