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geometry_utils.cpp
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geometry_utils.cpp
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//
// 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.
//
// geometry_utils:
// Helper library for generating certain sets of geometry.
//
#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 = static_cast<float>(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(static_cast<unsigned short>(i * (sliceCount + 1) + j));
result->indices.push_back(static_cast<unsigned short>((i + 1) * (sliceCount + 1) + j));
result->indices.push_back(
static_cast<unsigned short>((i + 1) * (sliceCount + 1) + (j + 1)));
result->indices.push_back(static_cast<unsigned short>(i * (sliceCount + 1) + j));
result->indices.push_back(
static_cast<unsigned short>((i + 1) * (sliceCount + 1) + (j + 1)));
result->indices.push_back(static_cast<unsigned short>(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;
}