axmol/core/3d/BillBoard.cpp

/****************************************************************************
 Copyright (c) 2014-2016 Chukong Technologies Inc.
 Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.

 https://axmol.dev/

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
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 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
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 THE SOFTWARE.
 ****************************************************************************/

#include "3d/BillBoard.h"
#include "2d/SpriteFrameCache.h"
#include "base/Director.h"
#include "2d/Camera.h"
#include "renderer/Renderer.h"

namespace ax
{

BillBoard::BillBoard() : _mode(Mode::VIEW_POINT_ORIENTED), _modeDirty(false)
{
    _trianglesCommand.setTransparent(true);
    _trianglesCommand.set3D(true);
    Node::setAnchorPoint(Vec2(0.5f, 0.5f));
}

BillBoard::~BillBoard() {}

BillBoard* BillBoard::createWithTexture(Texture2D* texture, Mode mode)
{
    BillBoard* billboard = new BillBoard();
    if (billboard->initWithTexture(texture))
    {
        billboard->_mode = mode;
        billboard->autorelease();
        return billboard;
    }
    AX_SAFE_DELETE(billboard);
    return nullptr;
}

BillBoard* BillBoard::create(std::string_view filename, Mode mode)
{
    BillBoard* billboard = new BillBoard();
    if (billboard->initWithFile(filename))
    {
        billboard->_mode = mode;
        billboard->autorelease();
        return billboard;
    }
    AX_SAFE_DELETE(billboard);
    return nullptr;
}

BillBoard* BillBoard::create(std::string_view filename, const Rect& rect, Mode mode)
{
    BillBoard* billboard = new BillBoard();
    if (billboard->initWithFile(filename, rect))
    {
        billboard->_mode = mode;
        billboard->autorelease();
        return billboard;
    }
    AX_SAFE_DELETE(billboard);
    return nullptr;
}

BillBoard* BillBoard::create(Mode mode)
{
    BillBoard* billboard = new BillBoard();
    if (billboard->init())
    {
        billboard->_mode = mode;
        billboard->autorelease();
        return billboard;
    }
    AX_SAFE_DELETE(billboard);
    return nullptr;
}

void BillBoard::visit(Renderer* renderer, const Mat4& parentTransform, uint32_t parentFlags)
{
    // quick return if not visible. children won't be drawn.
    if (!_visible)
    {
        return;
    }
    bool visibleByCamera = isVisitableByVisitingCamera();
    // quick return if not visible by camera and has no children.
    if (!visibleByCamera && _children.empty())
    {
        return;
    }

    uint32_t flags = processParentFlags(parentTransform, parentFlags);

    // Add 3D flag so all the children will be rendered as 3D object
    flags |= FLAGS_RENDER_AS_3D;

    // Update Billboard transform
    bool dirty = calculateBillboardTransform();
    if (dirty)
    {
        flags |= FLAGS_TRANSFORM_DIRTY;
    }

    _director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
    _director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW, _modelViewTransform);

    int i = 0;

    if (!_children.empty())
    {
        sortAllChildren();
        // draw children zOrder < 0
        for (auto size = _children.size(); i < size; ++i)
        {
            auto node = _children.at(i);

            if (node && node->getLocalZOrder() < 0)
                node->visit(renderer, _modelViewTransform, flags);
            else
                break;
        }
        // self draw
        if (visibleByCamera)
            this->draw(renderer, _modelViewTransform, flags);

        for (auto it = _children.cbegin() + i, itCend = _children.cend(); it != itCend; ++it)
            (*it)->visit(renderer, _modelViewTransform, flags);
    }
    else if (visibleByCamera)
    {
        this->draw(renderer, _modelViewTransform, flags);
    }

    _director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
}

bool BillBoard::calculateBillboardTransform()
{
    // Get camera world position
    auto camera             = Camera::getVisitingCamera();
    const Mat4& camWorldMat = camera->getNodeToWorldTransform();

    // TODO: use math lib to calculate math lib Make it easier to read and maintain
    if (memcmp(_camWorldMat.m, camWorldMat.m, sizeof(float) * 16) != 0 ||
        memcmp(_mvTransform.m, _modelViewTransform.m, sizeof(float) * 16) != 0 || _modeDirty || true)
    {
        // Rotate based on anchor point
        Vec3 anchorPoint(_anchorPointInPoints.x, _anchorPointInPoints.y, 0.0f);
        Mat4 localToWorld = _modelViewTransform;
        localToWorld.translate(anchorPoint);

        // Decide billboard mode
        Vec3 camDir;
        switch (_mode)
        {
        case Mode::VIEW_POINT_ORIENTED:
            camDir.set(localToWorld.m[12] - camWorldMat.m[12], localToWorld.m[13] - camWorldMat.m[13],
                       localToWorld.m[14] - camWorldMat.m[14]);
            break;
        case Mode::VIEW_PLANE_ORIENTED:
            camWorldMat.transformVector(Vec3(0.0f, 0.0f, -1.0f), &camDir);
            break;
        default:
            AXASSERT(false, "invalid billboard mode");
            break;
        }
        _modeDirty = false;

        if (camDir.length() < MATH_TOLERANCE)
        {
            camDir.set(camWorldMat.m[8], camWorldMat.m[9], camWorldMat.m[10]);
        }
        camDir.normalize();

        Mat4 rotationMatrix;
        rotationMatrix.setIdentity();

        Vec3 upAxis(rotationMatrix.m[4], rotationMatrix.m[5], rotationMatrix.m[6]);
        Vec3 x, y;
        camWorldMat.transformVector(upAxis, &y);
        Vec3::cross(camDir, y, &x);
        x.normalize();
        Vec3::cross(x, camDir, &y);
        y.normalize();

        float xlen = sqrtf(localToWorld.m[0] * localToWorld.m[0] + localToWorld.m[1] * localToWorld.m[1] +
                           localToWorld.m[2] * localToWorld.m[2]);
        float ylen = sqrtf(localToWorld.m[4] * localToWorld.m[4] + localToWorld.m[5] * localToWorld.m[5] +
                           localToWorld.m[6] * localToWorld.m[6]);
        float zlen = sqrtf(localToWorld.m[8] * localToWorld.m[8] + localToWorld.m[9] * localToWorld.m[9] +
                           localToWorld.m[10] * localToWorld.m[10]);

        Mat4 billboardTransform;

        billboardTransform.m[0]  = x.x * xlen;
        billboardTransform.m[1]  = x.y * xlen;
        billboardTransform.m[2]  = x.z * xlen;
        billboardTransform.m[4]  = y.x * ylen;
        billboardTransform.m[5]  = y.y * ylen;
        billboardTransform.m[6]  = y.z * ylen;
        billboardTransform.m[8]  = -camDir.x * zlen;
        billboardTransform.m[9]  = -camDir.y * zlen;
        billboardTransform.m[10] = -camDir.z * zlen;
        billboardTransform.m[12] = localToWorld.m[12];
        billboardTransform.m[13] = localToWorld.m[13];
        billboardTransform.m[14] = localToWorld.m[14];

        billboardTransform.translate(-anchorPoint);
        _mvTransform = _modelViewTransform = billboardTransform;

        _camWorldMat = camWorldMat;

        return true;
    }

    return false;
}

void BillBoard::draw(Renderer* renderer, const Mat4& /*transform*/, uint32_t flags)
{
    // FIXME: frustum culling here
    flags |= Node::FLAGS_RENDER_AS_3D;
    _trianglesCommand.init(0, _texture, _blendFunc, _polyInfo.triangles, _modelViewTransform, flags);
    setMVPMatrixUniform();  // update uniform
    renderer->addCommand(&_trianglesCommand);
}

void BillBoard::setMode(Mode mode)
{
    _mode      = mode;
    _modeDirty = true;
}

BillBoard::Mode BillBoard::getMode() const
{
    return _mode;
}

}