axmol/cocos/3d/CCFrustum.cpp

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 Copyright (c) 2014-2017 Chukong Technologies Inc.
 
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#include "3d/CCFrustum.h"
#include "2d/CCCamera.h"

NS_CC_BEGIN

bool Frustum::initFrustum(const Camera* camera)
{
    _initialized = true;
    createPlane(camera);
    return true;
}
bool Frustum::isOutOfFrustum(const AABB& aabb) const
{
    if (_initialized)
    {
        Vec3 point;

        int plane = _clipZ ? 6 : 4;
        for (int i = 0; i < plane; i++)
        {
            const Vec3& normal = _plane[i].getNormal();
            point.x = normal.x < 0 ? aabb._max.x : aabb._min.x;
            point.y = normal.y < 0 ? aabb._max.y : aabb._min.y;
            point.z = normal.z < 0 ? aabb._max.z : aabb._min.z;
            
            if (_plane[i].getSide(point) == PointSide::FRONT_PLANE )
                return true;
        }
    }
    return false;
}

bool Frustum::isOutOfFrustum(const OBB& obb) const
{
    if (_initialized)
    {
        Vec3 point;
        int plane = _clipZ ? 6 : 4;
        Vec3 obbExtentX = obb._xAxis * obb._extents.x;
        Vec3 obbExtentY = obb._yAxis * obb._extents.y;
        Vec3 obbExtentZ = obb._zAxis * obb._extents.z;
        
        for (int i = 0; i < plane; i++)
        {
            const Vec3& normal = _plane[i].getNormal();
            point = obb._center;
            point = normal.dot(obb._xAxis) > 0 ? point - obbExtentX : point + obbExtentX;
            point = normal.dot(obb._yAxis) > 0 ? point - obbExtentY : point + obbExtentY;
            point = normal.dot(obb._zAxis) > 0 ? point - obbExtentZ : point + obbExtentZ;

            if (_plane[i].getSide(point) == PointSide::FRONT_PLANE)
                return true;
        }
    }
    return  false;
}

void Frustum::createPlane(const Camera* camera)
{
    const Mat4& mat = camera->getViewProjectionMatrix();
    //ref http://www.lighthouse3d.com/tutorials/view-frustum-culling/clip-space-approach-extracting-the-planes/
    //extract frustum plane
    _plane[0].initPlane(-Vec3(mat.m[3] + mat.m[0], mat.m[7] + mat.m[4], mat.m[11] + mat.m[8]), (mat.m[15] + mat.m[12]));//left
    _plane[1].initPlane(-Vec3(mat.m[3] - mat.m[0], mat.m[7] - mat.m[4], mat.m[11] - mat.m[8]), (mat.m[15] - mat.m[12]));//right
    _plane[2].initPlane(-Vec3(mat.m[3] + mat.m[1], mat.m[7] + mat.m[5], mat.m[11] + mat.m[9]), (mat.m[15] + mat.m[13]));//bottom
    _plane[3].initPlane(-Vec3(mat.m[3] - mat.m[1], mat.m[7] - mat.m[5], mat.m[11] - mat.m[9]), (mat.m[15] - mat.m[13]));//top
    _plane[4].initPlane(-Vec3(mat.m[3] + mat.m[2], mat.m[7] + mat.m[6], mat.m[11] + mat.m[10]), (mat.m[15] + mat.m[14]));//near
    _plane[5].initPlane(-Vec3(mat.m[3] - mat.m[2], mat.m[7] - mat.m[6], mat.m[11] - mat.m[10]), (mat.m[15] - mat.m[14]));//far
}

NS_CC_END