samples/angle/sample_util/geometry_utils.cpp

//
// Copyright (c) 2014 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

#include "geometry_utils.h"

#define _USE_MATH_DEFINES
#include <math.h>

void CreateSphereGeometry(size_t sliceCount, float radius, SphereGeometry *result)
{
    size_t parellelCount = sliceCount / 2;
    size_t vertexCount = (parellelCount + 1) * (sliceCount + 1);
    size_t indexCount = parellelCount * sliceCount * 6;
    float angleStep = (2.0f * M_PI) / sliceCount;

    result->positions.resize(vertexCount);
    result->normals.resize(vertexCount);
    for (size_t i = 0; i < parellelCount + 1; i++)
    {
        for (size_t j = 0; j < sliceCount + 1; j++)
        {
            Vector3 direction(sinf(angleStep * i) * sinf(angleStep * j),
                              cosf(angleStep * i),
                              sinf(angleStep * i) * cosf(angleStep * j));

            size_t vertexIdx = i * (sliceCount + 1) + j;
            result->positions[vertexIdx] = direction * radius;
            result->normals[vertexIdx] = direction;
        }
    }

    result->indices.clear();
    result->indices.reserve(indexCount);
    for (size_t i = 0; i < parellelCount; i++)
    {
        for (size_t j = 0; j < sliceCount; j++)
        {
            result->indices.push_back( i      * (sliceCount + 1) +  j     );
            result->indices.push_back((i + 1) * (sliceCount + 1) +  j     );
            result->indices.push_back((i + 1) * (sliceCount + 1) + (j + 1));

            result->indices.push_back( i      * (sliceCount + 1) +  j     );
            result->indices.push_back((i + 1) * (sliceCount + 1) + (j + 1));
            result->indices.push_back( i      * (sliceCount + 1) + (j + 1));
        }
    }
}

void GenerateCubeGeometry(float radius, CubeGeometry *result)
{
    result->positions.resize(24);
    result->positions[ 0] = Vector3(-radius, -radius, -radius);
    result->positions[ 1] = Vector3(-radius, -radius,  radius);
    result->positions[ 2] = Vector3( radius, -radius,  radius);
    result->positions[ 3] = Vector3( radius, -radius, -radius);
    result->positions[ 4] = Vector3(-radius,  radius, -radius);
    result->positions[ 5] = Vector3(-radius,  radius,  radius);
    result->positions[ 6] = Vector3( radius,  radius,  radius);
    result->positions[ 7] = Vector3( radius,  radius, -radius);
    result->positions[ 8] = Vector3(-radius, -radius, -radius);
    result->positions[ 9] = Vector3(-radius,  radius, -radius);
    result->positions[10] = Vector3( radius,  radius, -radius);
    result->positions[11] = Vector3( radius, -radius, -radius);
    result->positions[12] = Vector3(-radius, -radius,  radius);
    result->positions[13] = Vector3(-radius,  radius,  radius);
    result->positions[14] = Vector3( radius,  radius,  radius);
    result->positions[15] = Vector3( radius, -radius,  radius);
    result->positions[16] = Vector3(-radius, -radius, -radius);
    result->positions[17] = Vector3(-radius, -radius,  radius);
    result->positions[18] = Vector3(-radius,  radius,  radius);
    result->positions[19] = Vector3(-radius,  radius, -radius);
    result->positions[20] = Vector3( radius, -radius, -radius);
    result->positions[21] = Vector3( radius, -radius,  radius);
    result->positions[22] = Vector3( radius,  radius,  radius);
    result->positions[23] = Vector3( radius,  radius, -radius);

    result->normals.resize(24);
    result->normals[ 0] = Vector3( 0.0f, -1.0f,  0.0f);
    result->normals[ 1] = Vector3( 0.0f, -1.0f,  0.0f);
    result->normals[ 2] = Vector3( 0.0f, -1.0f,  0.0f);
    result->normals[ 3] = Vector3( 0.0f, -1.0f,  0.0f);
    result->normals[ 4] = Vector3( 0.0f,  1.0f,  0.0f);
    result->normals[ 5] = Vector3( 0.0f,  1.0f,  0.0f);
    result->normals[ 6] = Vector3( 0.0f,  1.0f,  0.0f);
    result->normals[ 7] = Vector3( 0.0f,  1.0f,  0.0f);
    result->normals[ 8] = Vector3( 0.0f,  0.0f, -1.0f);
    result->normals[ 9] = Vector3( 0.0f,  0.0f, -1.0f);
    result->normals[10] = Vector3( 0.0f,  0.0f, -1.0f);
    result->normals[11] = Vector3( 0.0f,  0.0f, -1.0f);
    result->normals[12] = Vector3( 0.0f,  0.0f,  1.0f);
    result->normals[13] = Vector3( 0.0f,  0.0f,  1.0f);
    result->normals[14] = Vector3( 0.0f,  0.0f,  1.0f);
    result->normals[15] = Vector3( 0.0f,  0.0f,  1.0f);
    result->normals[16] = Vector3(-1.0f,  0.0f,  0.0f);
    result->normals[17] = Vector3(-1.0f,  0.0f,  0.0f);
    result->normals[18] = Vector3(-1.0f,  0.0f,  0.0f);
    result->normals[19] = Vector3(-1.0f,  0.0f,  0.0f);
    result->normals[20] = Vector3( 1.0f,  0.0f,  0.0f);
    result->normals[21] = Vector3( 1.0f,  0.0f,  0.0f);
    result->normals[22] = Vector3( 1.0f,  0.0f,  0.0f);
    result->normals[23] = Vector3( 1.0f,  0.0f,  0.0f);

    result->texcoords.resize(24);
    result->texcoords[ 0] = Vector2(0.0f, 0.0f);
    result->texcoords[ 1] = Vector2(0.0f, 1.0f);
    result->texcoords[ 2] = Vector2(1.0f, 1.0f);
    result->texcoords[ 3] = Vector2(1.0f, 0.0f);
    result->texcoords[ 4] = Vector2(1.0f, 0.0f);
    result->texcoords[ 5] = Vector2(1.0f, 1.0f);
    result->texcoords[ 6] = Vector2(0.0f, 1.0f);
    result->texcoords[ 7] = Vector2(0.0f, 0.0f);
    result->texcoords[ 8] = Vector2(0.0f, 0.0f);
    result->texcoords[ 9] = Vector2(0.0f, 1.0f);
    result->texcoords[10] = Vector2(1.0f, 1.0f);
    result->texcoords[11] = Vector2(1.0f, 0.0f);
    result->texcoords[12] = Vector2(0.0f, 0.0f);
    result->texcoords[13] = Vector2(0.0f, 1.0f);
    result->texcoords[14] = Vector2(1.0f, 1.0f);
    result->texcoords[15] = Vector2(1.0f, 0.0f);
    result->texcoords[16] = Vector2(0.0f, 0.0f);
    result->texcoords[17] = Vector2(0.0f, 1.0f);
    result->texcoords[18] = Vector2(1.0f, 1.0f);
    result->texcoords[19] = Vector2(1.0f, 0.0f);
    result->texcoords[20] = Vector2(0.0f, 0.0f);
    result->texcoords[21] = Vector2(0.0f, 1.0f);
    result->texcoords[22] = Vector2(1.0f, 1.0f);
    result->texcoords[23] = Vector2(1.0f, 0.0f);

    result->indices.resize(36);
    result->indices[ 0] =  0; result->indices[ 1] =  2; result->indices[ 2] =  1;
    result->indices[ 3] =  0; result->indices[ 4] =  3; result->indices[ 5] =  2;
    result->indices[ 6] =  4; result->indices[ 7] =  5; result->indices[ 8] =  6;
    result->indices[ 9] =  4; result->indices[10] =  6; result->indices[11] =  7;
    result->indices[12] =  8; result->indices[13] =  9; result->indices[14] = 10;
    result->indices[15] =  8; result->indices[16] = 10; result->indices[17] = 11;
    result->indices[18] = 12; result->indices[19] = 15; result->indices[20] = 14;
    result->indices[21] = 12; result->indices[22] = 14; result->indices[23] = 13;
    result->indices[24] = 16; result->indices[25] = 17; result->indices[26] = 18;
    result->indices[27] = 16; result->indices[28] = 18; result->indices[29] = 19;
    result->indices[30] = 20; result->indices[31] = 23; result->indices[32] = 22;
    result->indices[33] = 20; result->indices[34] = 22; result->indices[35] = 21;
}