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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.globaltime;
     18 
     19 public class LatLongSphere extends Sphere {
     20 
     21     public LatLongSphere(float centerX, float centerY, float centerZ,
     22         float radius, int lats, int longs,
     23         float minLongitude, float maxLongitude,
     24         boolean emitTextureCoordinates,
     25         boolean emitNormals,
     26         boolean emitColors,
     27         boolean flatten) {
     28         super(emitTextureCoordinates, emitNormals, emitColors);
     29 
     30         int tris = 2 * (lats - 1) * (longs - 1);
     31         int[] vertices = new int[3 * lats * longs];
     32         int[] texcoords = new int[2 * lats * longs];
     33         int[] colors = new int[4 * lats * longs];
     34         int[] normals = new int[3 * lats * longs];
     35         short[] indices = new short[3 * tris];
     36 
     37         int vidx = 0;
     38         int tidx = 0;
     39         int nidx = 0;
     40         int cidx = 0;
     41         int iidx = 0;
     42 
     43         minLongitude *= DEGREES_TO_RADIANS;
     44         maxLongitude *= DEGREES_TO_RADIANS;
     45 
     46         for (int i = 0; i < longs; i++) {
     47             float fi = (float) i / (longs - 1);
     48             // theta is the longitude
     49             float theta =
     50                 (maxLongitude - minLongitude) * (1.0f - fi) + minLongitude;
     51             float sinTheta = (float) Math.sin(theta);
     52             float cosTheta = (float) Math.cos(theta);
     53 
     54             for (int j = 0; j < lats; j++) {
     55                 float fj = (float) j / (lats - 1);
     56                 // phi is the latitude
     57                 float phi = PI * fj;
     58                 float sinPhi = (float) Math.sin(phi);
     59                 float cosPhi = (float) Math.cos(phi);
     60                 float x = cosTheta * sinPhi;
     61                 float y = cosPhi;
     62                 float z = sinTheta * sinPhi;
     63 
     64                 if (flatten) {
     65                     // Place vertices onto a flat projection
     66                     vertices[vidx++] = toFixed(2.0f * fi - 1.0f);
     67                     vertices[vidx++] = toFixed(0.5f - fj);
     68                     vertices[vidx++] = toFixed(0.0f);
     69                 } else {
     70                     // Place vertices onto the surface of a sphere
     71                     // with the given center and radius
     72                     vertices[vidx++] = toFixed(x * radius + centerX);
     73                     vertices[vidx++] = toFixed(y * radius + centerY);
     74                     vertices[vidx++] = toFixed(z * radius + centerZ);
     75                 }
     76 
     77                 if (emitTextureCoordinates) {
     78                     texcoords[tidx++] = toFixed(1.0f - (theta / (TWO_PI)));
     79                     texcoords[tidx++] = toFixed(fj);
     80                 }
     81 
     82                 if (emitNormals) {
     83                     float norm = 1.0f / Shape.length(x, y, z);
     84                     normals[nidx++] = toFixed(x * norm);
     85                     normals[nidx++] = toFixed(y * norm);
     86                     normals[nidx++] = toFixed(z * norm);
     87                 }
     88 
     89                 // 0 == black, 65536 == white
     90                 if (emitColors) {
     91                     colors[cidx++] = (i % 2) * 65536;
     92                     colors[cidx++] = 0;
     93                     colors[cidx++] = (j % 2) * 65536;
     94                     colors[cidx++] = 65536;
     95                 }
     96             }
     97         }
     98 
     99         for (int i = 0; i < longs - 1; i++) {
    100             for (int j = 0; j < lats - 1; j++) {
    101                 int base = i * lats + j;
    102 
    103                 // Ensure both triangles have the same final vertex
    104                 // since this vertex carries the color for flat
    105                 // shading
    106                 indices[iidx++] = (short) (base);
    107                 indices[iidx++] = (short) (base + 1);
    108                 indices[iidx++] = (short) (base + lats + 1);
    109 
    110                 indices[iidx++] = (short) (base + lats);
    111                 indices[iidx++] = (short) (base);
    112                 indices[iidx++] = (short) (base + lats + 1);
    113             }
    114         }
    115 
    116         allocateBuffers(vertices, texcoords, normals, colors, indices);
    117     }
    118 }
    119