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cocos_lib/cocos/primitive/Capsule.cpp

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/****************************************************************************
Copyright (c) 2021-2023 Xiamen Yaji Software Co., Ltd.
http://www.cocos.com
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
****************************************************************************/
#include "primitive/Capsule.h"
namespace cc {
IGeometry capsule(float radiusTop, float radiusBottom, float height, const ccstd::optional<ICapsuleOptions> &opts) {
const float torsoHeight = height - radiusTop - radiusBottom;
const uint32_t sides = opts.has_value() ? opts->sides : 32;
const uint32_t heightSegments = opts.has_value() ? opts->heightSegments : 32;
const float bottomProp = radiusBottom / height;
const float torProp = torsoHeight / height;
const float topProp = radiusTop / height;
const uint32_t bottomSegments = floor(static_cast<float>(heightSegments) * bottomProp);
const uint32_t topSegments = floor(static_cast<float>(heightSegments) * topProp);
const uint32_t torSegments = floor(static_cast<float>(heightSegments) * torProp);
const float topOffset = torsoHeight + radiusBottom - height / 2;
const float torOffset = radiusBottom - height / 2;
const float bottomOffset = radiusBottom - height / 2;
const float arc = opts.has_value() ? opts->arc : math::PI_2;
// calculate vertex count
ccstd::vector<float> positions;
ccstd::vector<float> normals;
ccstd::vector<float> uvs;
ccstd::vector<uint32_t> indices;
const float maxRadius = std::max(radiusTop, radiusBottom);
const Vec3 minPos(-maxRadius, -height / 2, -maxRadius);
const Vec3 maxPos(maxRadius, height / 2, maxRadius);
const float boundingRadius = height / 2;
uint32_t index = 0;
ccstd::vector<ccstd::vector<uint32_t>> indexArray;
// =======================
// internal functions
// =======================
auto generateTorso = [&]() {
// this will be used to calculate the normal
float slope = (radiusTop - radiusBottom) / torsoHeight;
// generate positions, normals and uvs
for (uint32_t y = 0; y <= torSegments; y++) {
ccstd::vector<uint32_t> indexRow;
const float lat = static_cast<float>(y) / static_cast<float>(torSegments);
const float radius = lat * (radiusTop - radiusBottom) + radiusBottom;
for (uint32_t x = 0; x <= sides; ++x) {
const float u = static_cast<float>(x) / static_cast<float>(sides);
const float v = lat * torProp + bottomProp;
const float theta = u * arc - (arc / 4);
const float sinTheta = sin(theta);
const float cosTheta = cos(theta);
// vertex
positions.emplace_back(radius * sinTheta);
positions.emplace_back(lat * torsoHeight + torOffset);
positions.emplace_back(radius * cosTheta);
// normal
Vec3 temp1(sinTheta, -slope, cosTheta);
temp1.normalize();
normals.emplace_back(temp1.x);
normals.emplace_back(temp1.y);
normals.emplace_back(temp1.z);
// uv
uvs.emplace_back(u);
uvs.emplace_back(v);
// save index of vertex in respective row
indexRow.emplace_back(index);
// increase index
++index;
}
// now save positions of the row in our index array
indexArray.emplace_back(indexRow);
}
// generate indices
for (uint32_t y = 0; y < torSegments; ++y) {
for (uint32_t x = 0; x < sides; ++x) {
// we use the index array to access the correct indices
const uint32_t i1 = indexArray[y][x];
const uint32_t i2 = indexArray[y + 1][x];
const uint32_t i3 = indexArray[y + 1][x + 1];
const uint32_t i4 = indexArray[y][x + 1];
// face one
indices.emplace_back(i1);
indices.emplace_back(i4);
indices.emplace_back(i2);
// face two
indices.emplace_back(i4);
indices.emplace_back(i3);
indices.emplace_back(i2);
}
}
};
auto generateBottom = [&]() {
for (uint32_t lat = 0; lat <= bottomSegments; ++lat) {
float theta = static_cast<float>(lat) * math::PI / static_cast<float>(bottomSegments) / 2;
float sinTheta = sin(theta);
float cosTheta = -cos(theta);
for (uint32_t lon = 0; lon <= sides; ++lon) {
const float phi = static_cast<float>(lon) * math::PI_2 / static_cast<float>(sides) - math::PI / 2;
const float sinPhi = sin(phi);
const float cosPhi = cos(phi);
const float x = sinPhi * sinTheta;
const float y = cosTheta;
const float z = cosPhi * sinTheta;
const float u = static_cast<float>(lon) / static_cast<float>(sides);
const float v = static_cast<float>(lat) / static_cast<float>(heightSegments);
positions.emplace_back(x * radiusBottom);
positions.emplace_back(y * radiusBottom + bottomOffset);
positions.emplace_back(z * radiusBottom);
normals.emplace_back(x);
normals.emplace_back(y);
normals.emplace_back(z);
uvs.emplace_back(u);
uvs.emplace_back(v);
if ((lat < bottomSegments) && (lon < sides)) {
const uint32_t seg1 = sides + 1;
const uint32_t a = seg1 * lat + lon;
const uint32_t b = seg1 * (lat + 1) + lon;
const uint32_t c = seg1 * (lat + 1) + lon + 1;
const uint32_t d = seg1 * lat + lon + 1;
indices.emplace_back(a);
indices.emplace_back(d);
indices.emplace_back(b);
indices.emplace_back(d);
indices.emplace_back(c);
indices.emplace_back(b);
}
++index;
}
}
};
auto generateTop = [&]() {
for (uint32_t lat = 0; lat <= topSegments; ++lat) {
const float theta = static_cast<float>(lat) * math::PI / static_cast<float>(topSegments) / 2 + math::PI / 2;
const float sinTheta = sin(theta);
const float cosTheta = -cos(theta);
for (uint32_t lon = 0; lon <= sides; ++lon) {
const float phi = static_cast<float>(lon) * 2 * math::PI / static_cast<float>(sides) - math::PI / 2;
const float sinPhi = sin(phi);
const float cosPhi = cos(phi);
const float x = sinPhi * sinTheta;
const float y = cosTheta;
const float z = cosPhi * sinTheta;
const float u = static_cast<float>(lon) / static_cast<float>(sides);
const float v = static_cast<float>(lat) / static_cast<float>(heightSegments) + (1 - topProp);
positions.emplace_back(x * radiusTop);
positions.emplace_back(y * radiusTop + topOffset);
positions.emplace_back(z * radiusTop);
normals.emplace_back(x);
normals.emplace_back(y);
normals.emplace_back(z);
uvs.emplace_back(u);
uvs.emplace_back(v);
if ((lat < topSegments) && (lon < sides)) {
const uint32_t seg1 = sides + 1;
const uint32_t a = seg1 * lat + lon + indexArray[torSegments][sides] + 1;
const uint32_t b = seg1 * (lat + 1) + lon + indexArray[torSegments][sides] + 1;
const uint32_t c = seg1 * (lat + 1) + lon + 1 + indexArray[torSegments][sides] + 1;
const uint32_t d = seg1 * lat + lon + 1 + indexArray[torSegments][sides] + 1;
indices.emplace_back(a);
indices.emplace_back(d);
indices.emplace_back(b);
indices.emplace_back(d);
indices.emplace_back(c);
indices.emplace_back(b);
}
}
}
};
generateBottom();
generateTorso();
generateTop();
IGeometry info;
info.positions = positions;
info.normals = normals;
info.uvs = uvs;
info.boundingRadius = boundingRadius;
info.minPos = minPos;
info.maxPos = maxPos;
info.indices = indices;
return info;
}
} // namespace cc