MetricSpacePolygon.java

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/*
 * Copyright (C) 2014 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package org.ros.android.view.visualization.shape;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;

import org.ros.android.view.visualization.Color;
import org.ros.android.view.visualization.Vertices;
import org.ros.android.view.visualization.VisualizationView;

import java.nio.FloatBuffer;
import java.util.List;

import javax.microedition.khronos.opengles.GL10;

public class MetricSpacePolygon extends BaseShape {

  final FloatBuffer vertexBuffer;
  final List<FloatBuffer> triangles;

  public MetricSpacePolygon(final float[] vertices, final Color color) {
    super();
    vertexBuffer = Vertices.toFloatBuffer(vertices);
    setColor(color);

    final List<Triangulate.Point> points = Lists.newArrayList();
    final Triangulate.Point[] contour = new Triangulate.Point[vertices.length / 3];
    for (int i = 0; i < contour.length; ++i) {
      contour[i] = new Triangulate.Point(vertices[i * 3], vertices[i * 3 + 1]);
    }
    Preconditions.checkState(Triangulate.process(contour, points));

    triangles = Lists.newArrayList();
    for (int i = 0; i < points.size() / 3; ++i) {
      final FloatBuffer triangle = Vertices.allocateBuffer(3 * 3);
      for (int j = i * 3; j < i * 3 + 3; ++j) {
        triangle.put(points.get(j).x());
        triangle.put(points.get(j).y());
        triangle.put(0.f);
      }
      triangle.flip();
      triangles.add(triangle);
    }
  }

  @Override
  public void drawShape(VisualizationView view, GL10 gl) {
    final Color translucent = getColor();
    translucent.setAlpha(0.3f);
    for (final FloatBuffer triangle : triangles) {
      Vertices.drawTriangleFan(gl, triangle, translucent);
    }
    final Color opaque = getColor();
    opaque.setAlpha(1.f);
    Vertices.drawLineLoop(gl, vertexBuffer, opaque, 3.f);
    Vertices.drawPoints(gl, vertexBuffer, opaque, 10.f);
  }
}