动态分配失败？ c++ [关闭]

Question

我正在尝试动态分配一个浮点数组 (distances)，但单步调试调试器显示它出于某种原因只分配了一个。 我已经尝试过 std::vector 并且它工作正常，但随后在Vec2 * points = Util::BCurvePerpPoint(i, p1, p2, p3, this->distances, this->m_NumGeoms * 2) 失败。问题是距离不会在对象的生命周期内改变大小，所以使用 std::vector 有点矫枉过正。我唯一使用 std::vector 的是 Draw 函数（我想我可以将其修复为静态大小或其他东西，但如果 step 发生变化，那么数组的大小将改变所以......是的......）。

注意：Util::BCurvePerpPoint 返回一个 Vec2 数组，其中第一个是贝塞尔曲线点 i。它所做的只是在贝塞尔曲线的切线的垂直线上提供点。函数原型：
BCurvePerpPoint(float time, Vec2 p1, Vec2 p2, Vec2 p3, float * distance, const int numDists);

标题：

#ifndef _H_HOLDTAIL_
#define _H_HOLDTAIL_
#pragma once
#include "../../OD_Draw2d.h"

namespace Game {
    struct HoldTailGeom {
        float d1,d2;
        ColorF color1, color2;
        uint32 packedCol1, packedCol2;

        HoldTailGeom() :
            d1(0.0f),
            d2(0.0f),
            color1(0.0f, 0.0f, 0.0f, 0.0f),
            color2(0.0f, 0.0f, 0.0f, 0.0f),
            packedCol1(0),
            packedCol2(0)
        {};
    };

    class HoldTail {
    public:
        HoldTail(HoldTailGeom * geoms, const unsigned int numGeoms);
        ~HoldTail();

        void Draw(Vec2 p1, Vec2 p2, Vec2 p3, float tStart, float tEnd, float step = 0.05f, bool isolatedDraw = false);
        void Draw(Vec2 p1, Vec2 p2, Vec2 p3, float tStart, float tEnd, int numPoints, bool isolatedDraw = false);
    private:
        HoldTailGeom * m_Geoms;
        unsigned int m_NumGeoms;
        float * distances;

        //std::vector<float> distances;

        std::shared_ptr<OD_Draw2d> OD_Draw2dPtr;
        std::vector<SVF_P3F_C4B_T2F> *line;
    };
}

#endif //_H_HOLDTAIL_

代码：

#include <StdAfx.h>
#include "HoldTail.h"

namespace Game {
    HoldTail::HoldTail(HoldTailGeom * geoms, const unsigned int numGeoms) : m_Geoms(geoms), m_NumGeoms(numGeoms) {
        this->line = new std::vector<SVF_P3F_C4B_T2F>[numGeoms];
        this->distances = new float[numGeoms * 2]();

        //distances = new std::vector<float>();

        for (int i = 0; i < numGeoms; i++) { //for each geometry
            //convert the colors to uint32 for quicker assignment to vector data.
            this->m_Geoms[i].packedCol1 = this->m_Geoms[i].color1.pack_argb8888();
            this->m_Geoms[i].packedCol2 = this->m_Geoms[i].color2.pack_argb8888();
            //convert the distances to an array that we can use.
            //int i1 = i * 2;
            //int i2 = (i * 2) + 1;
            this->distances[i * 2] = m_Geoms[i].d1;
            this->distances[(i * 2) + 1] = m_Geoms[i].d2;
            //this->distances.push_back(m_Geoms[i].d1);
            //this->distances.push_back(m_Geoms[i].d2);
        }

        //this->distances.shrink_to_fit();
    }

    HoldTail::~HoldTail() {
        for (int i = 0; i < this->m_NumGeoms; i++) this->line[i].clear(); //clear the data just to be sure.
        delete[] this->line;
        delete[] this->distances;
        //this->distances.clear();
    }

    void HoldTail::Draw(Vec2 p1, Vec2 p2, Vec2 p3, float tStart, float tEnd, int numPoints, bool isolatedDraw) {
        if (tStart >= tEnd) return;
        this->Draw(p1, p2, p3, tStart, tEnd, (float)((float)(tEnd - tStart) / (float)(numPoints)), isolatedDraw);
    }

    void HoldTail::Draw(Vec2 p1, Vec2 p2, Vec2 p3, float tStart, float tEnd, float step, bool isolatedDraw) {
        if (tStart >= tEnd) return;

        for (float i = tStart; i < tEnd+step; i += step) { //from start time to end time with a step between each
            Vec2 * points = Util::BCurvePerpPoint(i, p1, p2, p3, this->distances, this->m_NumGeoms * 2); //calculate the distances at time i.

            for (int i2 = 0; i2 < this->m_NumGeoms; i2++) { //for each geometry
                SVF_P3F_C4B_T2F tmp;

                //push back the vectors
                tmp.xyz = Vec3(points[(i2 * 2)+1].x, points[(i2 * 2)+1].y, 1);
                tmp.color.dcolor = this->m_Geoms[i2].packedCol1;
                tmp.st = Vec2(0, 0);
                this->line[i2].push_back(tmp);

                tmp.xyz = Vec3(points[(i2 * 2)+2].x, points[(i2 * 2)+2].y, 1);
                tmp.color.dcolor = this->m_Geoms[i2].packedCol2;
                this->line[i2].push_back(tmp);
            }
        }

        if (isolatedDraw) this->OD_Draw2dPtr->BeginDraw2d(1280, 720);
            for (int i = 0; i < this->m_NumGeoms; i++) { //for each geometry
                this->OD_Draw2dPtr->DrawTriangleStrip(&this->line[i][0], this->line[i].size()); //draw the line
                this->line[i].clear(); //done using the line, clear it for next pass.
            }
        if (isolatedDraw) this->OD_Draw2dPtr->EndDraw2d();
    }
}

Debugging Image

Answer 1

修复它... 显然m_Geoms 没有得到任何数据，即使在构造函数中我已经将它分配给m_Geoms(geoms)。 它没有复制数组... 于是我分别调整了构造函数和解构函数：

HoldTail::HoldTail(HoldTailGeom * geoms, const unsigned int numGeoms) : m_NumGeoms(numGeoms), distances(nullptr), line(nullptr) {
        this->line = new std::vector<SVF_P3F_C4B_T2F>[numGeoms];
        this->distances = new float[numGeoms * 2]();
        this->m_Geoms = new HoldTailGeom[numGeoms];

        //distances = new std::vector<float>();

        for (int i = 0; i < numGeoms; i++) { //for each geometry
            //copy data...
            this->m_Geoms[i].d1 = geoms[i].d1;
            this->m_Geoms[i].d2 = geoms[i].d2;
            this->m_Geoms[i].color1 = geoms[i].color1;
            this->m_Geoms[i].color2 = geoms[i].color2;
            //convert the colors to uint32 for quicker assignment to vector data.
            this->m_Geoms[i].packedCol1 = geoms[i].color1.pack_argb8888();
            this->m_Geoms[i].packedCol2 = geoms[i].color2.pack_argb8888();
            //convert the distances to an array that we can use.
            //int i1 = i * 2;
            //int i2 = (i * 2) + 1;
            this->distances[i * 2] = m_Geoms[i].d1;
            this->distances[(i * 2) + 1] = m_Geoms[i].d2;
            //this->distances.push_back(m_Geoms[i].d1);
            //this->distances.push_back(m_Geoms[i].d2);
        }

        //this->distances.shrink_to_fit();
    }

    HoldTail::~HoldTail() {
        for (int i = 0; i < this->m_NumGeoms; i++) this->line[i].clear(); //clear the data just to be sure.
        delete[] this->line;
        delete[] this->distances;
        delete[] this->m_Geoms;
        //this->distances.clear();
    }

解决了这个问题。 估计我在java上编程太久了……>.