Android example source code file (HeightMapMeshMaker.java)

This example Android source code file (HeightMapMeshMaker.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, bitmap, drawing, graphics, grid, heightmapmeshmaker, paint, ui

The HeightMapMeshMaker.java Android example source code

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * 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 com.android.heightmapprofiler;

import android.graphics.Bitmap;
import android.graphics.Color;

// This class generates vertex arrays based on grayscale images.
// It defines 1.0 (white) as the tallest point and 0.0 (black) as the lowest point,
// and builds a mesh that represents that topology.
public class HeightMapMeshMaker {

	public static final Grid makeGrid(Bitmap drawable, Bitmap lightmap, int subdivisions, float width, float height, float scale, boolean fixedPoint) {
    	Grid grid = null;
 
    	final float subdivisionRange = subdivisions - 1;
    	
    	final float vertexSizeX = width / subdivisionRange;
    	final float vertexSizeZ = height / subdivisionRange;
    	
    	if (drawable != null) {
    		grid = new Grid(subdivisions, subdivisions, fixedPoint);
    		final float heightMapScaleX = drawable.getWidth() / subdivisionRange;
    		final float heightMapScaleY = drawable.getHeight() / subdivisionRange;
    		final float lightMapScaleX = lightmap != null ? lightmap.getWidth() / subdivisions : 0.0f;
    		final float lightMapScaleY = lightmap != null ? lightmap.getHeight() / subdivisions : 0.0f;
    		
    		final float[] vertexColor = { 1.0f, 1.0f, 1.0f, 1.0f };
    		for (int i = 0; i < subdivisions; i++) {
    			final float u = (float)(i + 1) / subdivisions;
    			for (int j = 0; j < subdivisions; j++) {
    				final float v = (float)(j + 1) / subdivisions;
    	
    				final float vertexHeight = getBilinearFilteredHeight(drawable, (heightMapScaleX * i), (heightMapScaleY * j), scale);
    				
    				if (lightmap != null) {
    					final int lightColor = lightmap.getPixel((int)(lightMapScaleX * i), (int)(lightMapScaleY * j));
    					final float colorScale = 1.0f / 255.0f;
    					vertexColor[0] = colorScale * Color.red(lightColor);
    					vertexColor[1] = colorScale * Color.green(lightColor);
    					vertexColor[2] = colorScale * Color.blue(lightColor);
    					vertexColor[3] = colorScale * Color.alpha(lightColor);
    					
    				}
    				grid.set(i, j, i * vertexSizeX, vertexHeight, j * vertexSizeZ, u, v, vertexColor);
    			}
    		}
      	}
    	return grid;
    }
	
	// In order to get a smooth gradation between pixels from a low-resolution height map,
	// this function uses a bilinear filter to calculate a weighted average of four pixels
	// surrounding the requested point.
	public static final float getBilinearFilteredHeight(Bitmap drawable, float x, float y, float scale) {
		final int topLeftPixelX = clamp((int)Math.floor(x), 0, drawable.getWidth() - 1);
		final int topLeftPixelY = clamp((int)Math.floor(y), 0, drawable.getHeight() - 1);
		final int bottomRightPixelX = clamp((int)Math.ceil(x), 0, drawable.getWidth() - 1);
		final int bottomRightPixelY = clamp((int)Math.ceil(y), 0, drawable.getHeight() - 1);
		final float topLeftWeightX = x - topLeftPixelX;
		final float topLeftWeightY = y - topLeftPixelY;
		final float bottomRightWeightX = 1.0f - topLeftWeightX;
		final float bottomRightWeightY = 1.0f - topLeftWeightY;
		
		final int topLeft = drawable.getPixel(topLeftPixelX, topLeftPixelY);
		final int topRight = drawable.getPixel(bottomRightPixelX, topLeftPixelY);
		final int bottomLeft = drawable.getPixel(topLeftPixelX, bottomRightPixelY);
		final int bottomRight = drawable.getPixel(bottomRightPixelX, bottomRightPixelY);
		
		final float red1 = bottomRightWeightX * Color.red(topLeft) + topLeftWeightX * Color.red(topRight);
		final float red2 = bottomRightWeightX * Color.red(bottomLeft) + topLeftWeightX * Color.red(bottomRight);
		final float red = bottomRightWeightY * red1 + topLeftWeightY * red2;
		
		final float height = red * scale;
		return height;
		
	}
	
	private static final int clamp(int value, int min, int max) {
		return value < min ? min : (value > max ? max : value);
	}
}