填充实心多边形(一)

最新推荐文章于 2024-10-10 11:04:03 发布

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最新推荐文章于 2024-10-10 11:04:03 发布

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分类专栏： Graphics DirectX 文章标签： null buffer float struct application colors

本文链接：https://blog.youkuaiyun.com/lingang_/article/details/2892694

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可以利用前一篇文章中的Cohen-Sutherland裁剪算法对缓冲区的任意图形画出经裁剪的该图形，那么接下来该如何填充这些图形(一般是多边形)。若是四边形，我们可以把它分解成2个三角形。而对于任意三角形，又可以分解成一个平底三角形和一个平顶三角形。接下来给出填充任意三角形的代码，摘自《windows游戏编程大师技巧》。

 
 /* 2008/9/4
代码功能:填充任意三角形
并经过矩形裁剪*/
#define WIN32_LEAN_AND_MEAN   //不使用MFC 
#define INITGUID      //使用GUID 
#include <windows.h> 
#include <windowsx.h> 
#include <mmsystem.h> //多媒体API 
#include <iostream.h> 
#include <conio.h>    //控制台IO支持 
#include <stdlib.h>   //声明定义的一些常用标准函数库 
#include <malloc.h>   //声明或定义一些内存的函数 
#include <memory.h>   //提供了内存操作相关的一些函数及声明 
#include <string.h>   //字符串的一些功能 
#include <stdarg.h>   //defines ANSI-style macros for variable argument functions 
#include <stdio.h>    //efinitions/declarations for standard I/O routines 
#include <math.h>     //一些数学方法 
#include <io.h>       //declarations for low-level file handling and I/O functions 
#include <fcntl.h>    //file control options used by open() 
#include <ddraw.h> 
//windows类名 
#define  WINDOW_CLASS_NAME "WINCLASS1" 
//宽,高,色深(像素) 
#define  SCREEN_WIDTH   640 
#define  SCREEN_HEIGHT   480 
#define  SCREEN_BPP     8 
#define  MAX_COLORS_PALETTE   256 
typedef unsigned short USHORT;
typedef unsigned short WORD;
typedef unsigned char UCHAR;
typedef unsigned char BYTE;
//GDI文字函数 
int Draw_Text_GDI(char* text,int x,int y,int color,LPDIRECTDRAWSURFACE7 lpdds);
//填充表面 
int DDraw_Fill_Surface(LPDIRECTDRAWSURFACE7 lpdds,int color);
//填充任意三角形 
void Draw_Triangle_2D(int x1,int y1,int x2,int y2,int x3,int y3,int color,UCHAR *dest_buffer,int mempitch);
//填充平顶三角形 
void Draw_Top_Tri(int x1,int y1,int x2,int y2,int x3,int y3,int color,UCHAR *dest_buffer,int mempitch);
//填充平底三角形 
void Draw_Bottom_Tri(int x1,int y1,int x2,int y2,int x3,int y3,int color,UCHAR *dest_buffer,int mempitch);
//键盘按键宏 
#define  KEYDOWN(vk_code) ((GetAsyncKeyState(vk_code)&0x8000)?1:0) 
#define  KEYUP(vk_code)   ((GetAsyncKeyState(vk_code)&0x8000)?0:1) 
//初始化结构体 
#define  DDRAW_INIT_STRUCT(ddstruct) { memset(&ddstruct,0,sizeof(ddstruct));ddstruct.dwSize=sizeof(ddstruct); } 
HWND main_window_handle =NULL;
int  window_closed =0;
HINSTANCE hinstance_app =NULL;
LPDIRECTDRAW7 lpdd =NULL;
LPDIRECTDRAWSURFACE7 lpddsprimary =NULL;  //主缓存 
LPDIRECTDRAWSURFACE7 lpddsback =NULL;     //后备缓冲 
LPDIRECTDRAWPALETTE  lpddpal =NULL;       //调色板接口 
LPDIRECTDRAWCLIPPER  lpddclipper =NULL;   //裁剪器 
PALETTEENTRY         palette[256];        //调色板 
DDSURFACEDESC2       ddsd;
DDBLTFX              ddbltfx;
DDSCAPS2             ddscaps;
/*裁剪区域*/
int min_clip_x = 0,
    max_clip_x =SCREEN_WIDTH-1, 
    min_clip_y = 0,
    max_clip_y = SCREEN_HEIGHT-1;
char buffer[80];
int Draw_Text_GDI(char* text,int x,int y,int color,LPDIRECTDRAWSURFACE7 lpdds)
{
  HDC xdc;
  if(FAILED(lpdds->GetDC(&xdc)))
    return(0);
  SetTextColor(xdc,RGB(palette[color].peRed,palette[color].peGreen,palette[color].peBlue));
  SetBkMode(xdc,TRANSPARENT);
  TextOut(xdc,x,y,text,strlen(text));
  lpdds->ReleaseDC(xdc);
  return(1);
}
int DDraw_Fill_Surface(LPDIRECTDRAWSURFACE7 lpdds,int color)
{
  DDRAW_INIT_STRUCT(ddbltfx);
  ddbltfx.dwFillColor=color;
  lpdds->Blt(NULL,
             NULL,
             NULL,
             DDBLT_COLORFILL|DDBLT_WAIT,
             &ddbltfx);
  return(1);
}
//填充平顶三角形 
void Draw_Top_Tri(int x1,int y1,
                  int x2,int y2,
                  int x3,int y3,
                  int color,
                  UCHAR *dest_buffer,int mempitch)
{
  float dx_right,
        dx_left,
        xs,xe,
        height;
  int temp_x,
      temp_y,
      right,
      left;
  UCHAR *dest_addr=NULL;
  if (x2<x1)
  {
    temp_x=x2;
    x2=x1;
    x1=temp_x;
  }
  height=y3-y1;
  dx_left=(x3-x1)/height;
  dx_right=(x3-x2)/height;
  xs=(float)x1;
  xe=(float)x2;
  if(y1<min_clip_y)
  {
    xs=xs+dx_left*(float)(-y1+min_clip_y);
    xe=xe+dx_right*(false)(-y1+min_clip_y);
    y1=min_clip_y;
  }
  if(y3>max_clip_y)
    y3=max_clip_y;
  dest_addr=dest_buffer+y1*mempitch;
  if(x1>min_clip_x&&x1<max_clip_x&
      x2>min_clip_x&&x2<max_clip_x&
      x3>min_clip_x&&x3<max_clip_x)
  {/*若三角形完全在裁剪区域内*/
    for (temp_y=y1;temp_y<=y3;temp_y++,dest_addr+=mempitch)
    {
      memset((UCHAR*)dest_addr+(size_t)xs,color,(size_t)(xe-xs+1));
      xs+=dx_left;
      xe+=dx_right;
    }
  }
  else
  {/*三角形有落在裁剪区域外的部分*/
    for (temp_y=y1;temp_y<=y3;temp_y++,dest_addr+=mempitch)
    {
      left=(int)xs;
      right=(int)xe;
      xs+=dx_left;
      xe+=dx_right;
      if(left<min_clip_x)
      {
        left=min_clip_x;
        if(right<min_clip_x)
          continue;
      }
      if(right>max_clip_x)
      {
        right=max_clip_x;
        if(left>max_clip_x)
          continue;
      }
      memset((UCHAR*)dest_addr+(size_t)left,color,(size_t)(right-left+1));
    }
  }
}
//填充平底三角形 
void Draw_Bottom_Tri(int x1,int y1, 
                     int x2,int y2, 
                     int x3,int y3,
                     int color,
                     UCHAR *dest_buffer, int mempitch)
{
// this function draws a triangle that has a flat bottom 
float dx_right,    // the dx/dy ratio of the right edge of line 
      dx_left,     // the dx/dy ratio of the left edge of line 
      xs,xe,       // the starting and ending points of the edges 
      height;      // the height of the triangle 
int temp_x,        // used during sorting as temps 
    temp_y,
    right,         // used by clipping 
    left;
// destination address of next scanline 
UCHAR  *dest_addr;
// test order of x1 and x2 
if (x3 < x2)
   {
   temp_x = x2;
   x2     = x3;
   x3     = temp_x;
   } // end if swap 
// compute delta's 
height = y3-y1;
dx_left  = (x2-x1)/height;
dx_right = (x3-x1)/height;
// set starting points 
xs = (float)x1;
xe = (float)x1; // +(float)0.5; 
// perform y clipping 
if (y1<min_clip_y)
   {
   // compute new xs and ys 
   xs = xs+dx_left*(float)(-y1+min_clip_y);
   xe = xe+dx_right*(float)(-y1+min_clip_y);
   // reset y1 
   y1=min_clip_y;
   } // end if top is off screen 
if (y3>max_clip_y)
   y3=max_clip_y;
// compute starting address in video memory 
dest_addr = dest_buffer+y1*mempitch;
// test if x clipping is needed 
if (x1>=min_clip_x && x1<=max_clip_x &
    x2>=min_clip_x && x2<=max_clip_x &
    x3>=min_clip_x && x3<=max_clip_x)
    {
    // draw the triangle 
    for (temp_y=y1; temp_y<=y3; temp_y++,dest_addr+=mempitch)
        {
        memset((UCHAR  *)dest_addr+(unsigned int)xs,
                color,(unsigned int)(xe-xs+1));
        // adjust starting point and ending point 
        xs+=dx_left;
        xe+=dx_right;
        } // end for 
    } // end if no x clipping needed 
else
   {
   // clip x axis with slower version 
   // draw the triangle 
   for (temp_y=y1; temp_y<=y3; temp_y++,dest_addr+=mempitch)
       {
       // do x clip 
       left  = (int)xs;
       right = (int)xe;
       // adjust starting point and ending point 
       xs+=dx_left;
       xe+=dx_right;
       // clip line 
       if (left < min_clip_x)
          {
          left = min_clip_x;
          if (right < min_clip_x)
             continue;
          }
       if (right > max_clip_x)
          {
          right = max_clip_x;
          if (left > max_clip_x)
             continue;
          }
       memset((UCHAR  *)dest_addr+(unsigned int)left,
              color,(unsigned int)(right-left+1));
       } // end for 
   } // end else x clipping needed 
} // end Draw_Bottom_Tri 
//填充三角形 
void Draw_Triangle_2D(int x1,int y1,
                      int x2,int y2,
                      int x3,int y3,
                      int color,
                      UCHAR *dest_buffer,int mempitch)
{
  int temp_x,
      temp_y,
      new_x;
  //三角形x||y坐标在同一直线 
  if ((x1==x2&&x2==x3)||(y1==y2&&y2==y3))
    return;
  //确定三角形三点的位置 
  if (y2<y1)
  {
    temp_x=x2;
    temp_y=y2;
    x2=x1;
    y2=y1;
    x1=temp_x;
    y1=temp_y;
  }
  if (y3<y1)
  {
    temp_x=x3;
    temp_y=y3;
    x3=x1;
    y3=y1;
    x1=temp_x;
    y1=temp_y;
  }
  if (y3<y2)
  {
    temp_x=x3;
    temp_y=y3;
    x3=x2;
    y3=y2;
    x2=temp_x;
    y2=temp_y;
  }
  if (y3<min_clip_y||y1>max_clip_y||
      (x1<min_clip_x&&x2<min_clip_x&&x3<min_clip_x)||
      (x1>max_clip_x&&x2>max_clip_x&&x3>max_clip_x))
      return;
  if(y1==y2)
    Draw_Top_Tri(x1,y1,x2,y2,x3,y3,color,dest_buffer,mempitch);
  else
  if(y2==y3)
    Draw_Bottom_Tri(x1,y1,x2,y2,x3,y3,color,dest_buffer,mempitch);
  else
  {/*三角形是任意的*/
    new_x=x1+(int)(0.5+(float)(y2-y1)*(float)(x3-x1)/(float)(y3-y1));
    Draw_Bottom_Tri(x1,y1,new_x,y2,x2,y2,color,dest_buffer,mempitch);
    Draw_Top_Tri(x2,y2,new_x,y2,x3,y3,color,dest_buffer,mempitch);
  }
  
}
LRESULT CALLBACK WindowProc(HWND hwnd,
                            UINT msg,
                            WPARAM wparam,
                            LPARAM lparam)
{
PAINTSTRUCT     ps;     
HDC             hdc;    
       
switch(msg)
    {   
    case WM_CREATE: 
        {
        return(0);
        } break;
   
    case WM_PAINT: 
        {
        hdc = BeginPaint(hwnd,&ps);  
        
        EndPaint(hwnd,&ps);
        return(0);
        } break;
    case WM_DESTROY: 
        {
        PostQuitMessage(0);
        return(0);
        } break;
    default:break;
    }
return (DefWindowProc(hwnd, msg, wparam, lparam));
}
int Game_Init(void *parms=NULL,int num_parms=0)
{
  if(FAILED(DirectDrawCreateEx(NULL,(void **)&lpdd,IID_IDirectDraw7,NULL)))
    return(0);
  if(FAILED(lpdd->SetCooperativeLevel(main_window_handle,
                                      DDSCL_FULLSCREEN|DDSCL_ALLOWMODEX|
                                      DDSCL_EXCLUSIVE|DDSCL_ALLOWREBOOT)))
    return(0);
  if(FAILED(lpdd->SetDisplayMode(SCREEN_WIDTH,SCREEN_HEIGHT,SCREEN_BPP,0,0)))
    return(0);
  DDRAW_INIT_STRUCT(ddsd);
  ddsd.dwFlags=DDSD_CAPS | DDSD_BACKBUFFERCOUNT;
  ddsd.dwBackBufferCount=1;
  ddsd.ddsCaps.dwCaps=DDSCAPS_PRIMARYSURFACE|DDSCAPS_COMPLEX|
                        DDSCAPS_FLIP;
  
  if(FAILED(lpdd->CreateSurface(&ddsd,&lpddsprimary,NULL)))
    return(0);
  ddsd.ddsCaps.dwCaps=DDSCAPS_BACKBUFFER;
  if(FAILED(lpddsprimary->GetAttachedSurface(&ddsd.ddsCaps,&lpddsback)))
    return(0);
  for (int color=1; color < 255; color++)
    {
    palette[color].peRed   = rand()%256;
    palette[color].peGreen = rand()%256;
    palette[color].peBlue  = rand()%256;
    palette[color].peFlags = PC_NOCOLLAPSE;
    } 
palette[0].peRed     = 0;
palette[0].peGreen   = 0;
palette[0].peBlue    = 0;
palette[0].peFlags   = PC_NOCOLLAPSE;
palette[255].peRed   = 255;
palette[255].peGreen = 255;
palette[255].peBlue  = 255;
palette[255].peFlags = PC_NOCOLLAPSE;
palette[1].peRed     = 255;
palette[1].peGreen   = 0;
palette[1].peBlue    = 0;
palette[1].peFlags   = PC_NOCOLLAPSE;
if(FAILED(lpdd->CreatePalette(DDPCAPS_8BIT|DDPCAPS_ALLOW256|
                              DDPCAPS_INITIALIZE,palette,&lpddpal,NULL)))
    return(0);
if(FAILED(lpddsprimary->SetPalette(lpddpal)))
    return(0);
DDraw_Fill_Surface(lpddsprimary,0);
DDraw_Fill_Surface(lpddsback,0);
return(1);  
}
int Game_Main(void *parms = NULL, int num_parms = 0)
{
  if(window_closed)
    return(0);
  if(KEYDOWN(VK_ESCAPE))
  {
    PostMessage(main_window_handle,WM_CLOSE,0,0);
    window_closed=1;
  }
  DDraw_Fill_Surface(lpddsback,0);
  DDRAW_INIT_STRUCT(ddsd);
  if(FAILED(lpddsback->Lock(NULL,&ddsd,DDLOCK_WAIT|DDLOCK_SURFACEMEMORYPTR,NULL)))
    return(0);
  Draw_Triangle_2D(rand()%SCREEN_WIDTH, rand()%SCREEN_HEIGHT,
                 rand()%SCREEN_WIDTH, rand()%SCREEN_HEIGHT,
                 rand()%SCREEN_WIDTH, rand()%SCREEN_HEIGHT,
                 rand()%256,(UCHAR *)ddsd.lpSurface, ddsd.lPitch);
  if (FAILED(lpddsback->Unlock(NULL)))
   return(0);
while(FAILED(lpddsprimary->Flip(NULL,DDFLIP_WAIT)));
  
Sleep(33);
return(1);
}
int Game_Shutdown(void *parms = NULL, int num_parms = 0)
{/*清除资源*/
if (lpddpal)
   {
   lpddpal->Release();
   lpddpal = NULL;
   }
if(lpddsback)
  {
  lpddsback->Release();
  lpddsback=NULL;
  }
if (lpddsprimary)
   {
   lpddsprimary->Release();
   lpddsprimary = NULL;
   } 
if (lpdd)
   {
   lpdd->Release();
   lpdd = NULL;
   } 
return(1);
}
int WINAPI WinMain( HINSTANCE hinstance,
                    HINSTANCE hprevinstance,
                    LPSTR lpcmdline,
                    int ncmdshow)
{
WNDCLASSEX winclass; 
HWND       hwnd;    
MSG        msg;      
//HDC        hdc;     
winclass.cbSize         = sizeof(WNDCLASSEX);
winclass.style          = CS_DBLCLKS | CS_OWNDC | 
                          CS_HREDRAW | CS_VREDRAW;
winclass.lpfnWndProc    = WindowProc;
winclass.cbClsExtra     = 0;
winclass.cbWndExtra     = 0;
winclass.hInstance      = hinstance;
winclass.hIcon          = LoadIcon(NULL, IDI_APPLICATION);
winclass.hCursor        = LoadCursor(NULL, IDC_ARROW); 
winclass.hbrBackground  = (HBRUSH)GetStockObject(BLACK_BRUSH);
winclass.lpszMenuName   = NULL;
winclass.lpszClassName  = WINDOW_CLASS_NAME;
winclass.hIconSm        = LoadIcon(NULL, IDI_APPLICATION);
hinstance_app = hinstance;
if (!RegisterClassEx(&winclass))
    return(0);
if (!(hwnd = CreateWindowEx(NULL,                  
                            WINDOW_CLASS_NAME,    
                            "DirectDraw 8-Bit Line Drawing Demo", 
                            WS_POPUP | WS_VISIBLE,
                            0,0,    
                            SCREEN_WIDTH,SCREEN_HEIGHT,  
                            NULL,     
                            NULL,  
                            hinstance,
                            NULL))) 
return(0);
main_window_handle = hwnd;
Game_Init();
while(TRUE)
    {
  
    if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))
       { 
       if (msg.message == WM_QUIT)
           break;
    
       TranslateMessage(&msg);
       DispatchMessage(&msg);
       }
     Game_Main();
       
    } 
Game_Shutdown();
return(msg.wParam);
}

若是四边形则可以分解成2个三角形来进行填充。

 
 inline void Draw_Quad_2D(int x0,int y0,
                    int x1,int y1,
                    int x2,int y2,
                    int x3, int y3,
                    int color,
                    UCHAR *dest_buffer, int mempitch)
{//填充任意四边形 
Draw_Triangle_2D(x0,y0,x1,y1,x3,y3,color,dest_buffer,mempitch);
Draw_Triangle_2D(x1,y1,x2,y2,x3,y3,color,dest_buffer,mempitch);
}