求消隐算法里的扫描线算法的visual c++编程

Question

扫描线算法，最好是两个三角形，我们的计算机图形学要展示，我不会编程，有没有大神帮忙，程序最好是全的，不能只有一部分，实在不行，一部分也行！急急急

Answer 1

该回答引用ChatGPT-3.5，仅供参考，不保证完全正确

以下是一个使用扫描线算法绘制两个三角形的示例程序，使用Visual C++编写：

#include <Windows.h>
#include <iostream>
#include <vector>

using namespace std;

struct Point {
    int x;
    int y;

    Point(int xCoord, int yCoord) : x(xCoord), y(yCoord) {}
};

void DrawLine(HDC hdc, int x1, int y1, int x2, int y2) {
    MoveToEx(hdc, x1, y1, NULL);
    LineTo(hdc, x2, y2);
}

void DrawTriangle(HDC hdc, Point p1, Point p2, Point p3) {
    DrawLine(hdc, p1.x, p1.y, p2.x, p2.y);
    DrawLine(hdc, p2.x, p2.y, p3.x, p3.y);
    DrawLine(hdc, p3.x, p3.y, p1.x, p1.y);
}

void ScanlineFill(HDC hdc, Point p1, Point p2, Point p3) {
    vector<int> ymin, ymax;
    int miny = min(p1.y, min(p2.y, p3.y));
    int maxy = max(p1.y, max(p2.y, p3.y));

    ymin.resize(maxy + 1, INT_MAX);
    ymax.resize(maxy + 1, INT_MIN);

    // 计算每条扫描线与三角形的交点
    for (int i = 0; i < 3; i++) {
        int x1 = -1, y1 = -1, x2 = -1, y2 = -1;

        switch (i) {
            case 0:
                x1 = p1.x;
                y1 = p1.y;
                x2 = p2.x;
                y2 = p2.y;
                break;
            case 1:
                x1 = p2.x;
                y1 = p2.y;
                x2 = p3.x;
                y2 = p3.y;
                break;
            case 2:
                x1 = p3.x;
                y1 = p3.y;
                x2 = p1.x;
                y2 = p1.y;
                break;
        }

        if (y1 == y2) {
            continue;  // 忽略水平边
        }

        if (y1 > y2) {
            swap(x1, x2);
            swap(y1, y2);
        }

        int dy = y2 - y1;
        int dx = x2 - x1;
        int sign = (dx * dy >= 0) ? 1 : -1;
        int x = x1;
        int y = y1;

        for (; y <= y2; y++) {
            int xend = x + sign * (static_cast<double>(y - y1) / dy) * dx;
            ymin[y] = min(ymin[y], xend);
            ymax[y] = max(ymax[y], xend);
        }
    }

    // 填充三角形
    for (int y = miny; y <= maxy; y++) {
        if (ymin[y] <= ymax[y]) {
            for (int x = ymin[y]; x <= ymax[y]; x++) {
                SetPixel(hdc, x, y, RGB(0, 0, 0));  // 使用黑色填充
            }
        }
    }
}

LRESULT CALLBACK

 WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {
    HDC hdc;
    PAINTSTRUCT ps;

    switch (message) {
        case WM_PAINT:
            hdc = BeginPaint(hWnd, &ps);
            {
                Point p1(100, 100);
                Point p2(200, 200);
                Point p3(150, 300);

                DrawTriangle(hdc, p1, p2, p3);
                ScanlineFill(hdc, p1, p2, p3);
            }
            EndPaint(hWnd, &ps);
            break;
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
        default:
            return DefWindowProc(hWnd, message, wParam, lParam);
    }

    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
    WNDCLASSEX wcex;
    HWND hWnd;
    MSG msg;

    // 注册窗口类
    ZeroMemory(&wcex, sizeof(wcex));
    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.hInstance = hInstance;
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wcex.lpszClassName = L"ScanlineAlgorithm";
    if (!RegisterClassEx(&wcex)) {
        MessageBox(NULL, L"注册窗口类失败！", L"错误", MB_ICONERROR);
        return 1;
    }

    // 创建窗口
    hWnd = CreateWindow(
        L"ScanlineAlgorithm", L"Scanline Algorithm", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT,
        500, 500, NULL, NULL, hInstance, NULL
    );
    if (!hWnd) {
        MessageBox(NULL, L"创建窗口失败！", L"错误", MB_ICONERROR);
        return 1;
    }

    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

    // 消息循环
    while (GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return (int)msg.wParam;
}

这个程序创建一个窗口并使用扫描线算法绘制两个三角形，然后使用黑色填充这两个三角形。你可以将代码复制到Visual Studio中的新项目中，并将其作为Win32控制台应用程序构建和运行。