demo8_7.cpp

《Windows游戏编程大师技巧（第二版）》源代码

xe = (float)x2+(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_Top_Tri

/////////////////////////////////////////////////////////////////////////////

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

///////////////////////////////////////////////////////////////////////////////

void Draw_TriangleFP_2D(int x1,int y1,
                        int x2,int y2,
                        int x3,int y3,
                        int color,
    	   			    UCHAR *dest_buffer, int mempitch)
{
// this function draws a triangle on the destination buffer using fixed point
// it decomposes all triangles into a pair of flat top, flat bottom

int temp_x, // used for sorting
    temp_y,
    new_x;

// test for h lines and v lines
if ((x1==x2 && x2==x3)  ||  (y1==y2 && y2==y3))
   return;

// sort p1,p2,p3 in ascending y order
if (y2<y1)
   {
   temp_x = x2;
   temp_y = y2;
   x2     = x1;
   y2     = y1;
   x1     = temp_x;
   y1     = temp_y;
   } // end if

// now we know that p1 and p2 are in order
if (y3<y1)
   {
   temp_x = x3;
   temp_y = y3;
   x3     = x1;
   y3     = y1;
   x1     = temp_x;
   y1     = temp_y;
   } // end if

// finally test y3 against y2
if (y3<y2)
   {
   temp_x = x3;
   temp_y = y3;
   x3     = x2;
   y3     = y2;
   x2     = temp_x;
   y2     = temp_y;

   } // end if

// do trivial rejection tests for clipping
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;

// test if top of triangle is flat
if (y1==y2)
   {
   Draw_Top_TriFP(x1,y1,x2,y2,x3,y3,color, dest_buffer, mempitch);
   } // end if
else
if (y2==y3)
   {
   Draw_Bottom_TriFP(x1,y1,x2,y2,x3,y3,color, dest_buffer, mempitch);
   } // end if bottom is flat
else
   {
   // general triangle that's needs to be broken up along long edge
   new_x = x1 + (int)(0.5+(float)(y2-y1)*(float)(x3-x1)/(float)(y3-y1));

   // draw each sub-triangle
   Draw_Bottom_TriFP(x1,y1,new_x,y2,x2,y2,color, dest_buffer, mempitch);
   Draw_Top_TriFP(x2,y2,new_x,y2,x3,y3,color, dest_buffer, mempitch);

   } // end else

} // end Draw_TriangleFP_2D

/////////////////////////////////////////////////////////////

void Draw_Triangle_2D(int x1,int y1,
                      int x2,int y2,
                      int x3,int y3,
                      int color,
					  UCHAR *dest_buffer, int mempitch)
{
// this function draws a triangle on the destination buffer
// it decomposes all triangles into a pair of flat top, flat bottom

int temp_x, // used for sorting
    temp_y,
    new_x;

// test for h lines and v lines
if ((x1==x2 && x2==x3)  ||  (y1==y2 && y2==y3))
   return;

// sort p1,p2,p3 in ascending y order
if (y2<y1)
   {
   temp_x = x2;
   temp_y = y2;
   x2     = x1;
   y2     = y1;
   x1     = temp_x;
   y1     = temp_y;
   } // end if

// now we know that p1 and p2 are in order
if (y3<y1)
   {
   temp_x = x3;
   temp_y = y3;
   x3     = x1;
   y3     = y1;
   x1     = temp_x;
   y1     = temp_y;
   } // end if

// finally test y3 against y2
if (y3<y2)
   {
   temp_x = x3;
   temp_y = y3;
   x3     = x2;
   y3     = y2;
   x2     = temp_x;
   y2     = temp_y;

   } // end if

// do trivial rejection tests for clipping
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;

// test if top of triangle is flat
if (y1==y2)
   {
   Draw_Top_Tri(x1,y1,x2,y2,x3,y3,color, dest_buffer, mempitch);
   } // end if
else
if (y2==y3)
   {
   Draw_Bottom_Tri(x1,y1,x2,y2,x3,y3,color, dest_buffer, mempitch);
   } // end if bottom is flat
else
   {
   // general triangle that's needs to be broken up along long edge
   new_x = x1 + (int)(0.5+(float)(y2-y1)*(float)(x3-x1)/(float)(y3-y1));

   // draw each sub-triangle
   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);

   } // end else

} // end Draw_Triangle_2D

////////////////////////////////////////////////////////////////////////////////


int Draw_Text_GDI(char *text, int x,int y,int color, LPDIRECTDRAWSURFACE7 lpdds)
{
// this function draws the sent text on the sent surface 
// using color index as the color in the palette

HDC xdc; // the working dc

// get the dc from surface
if (FAILED(lpdds->GetDC(&xdc)))
   return(0);

// set the colors for the text up
SetTextColor(xdc,RGB(palette[color].peRed,palette[color].peGreen,palette[color].peBlue) );

// set background mode to transparent so black isn't copied
SetBkMode(xdc, TRANSPARENT);

// draw the text a
TextOut(xdc,x,y,text,strlen(text));

// release the dc
lpdds->ReleaseDC(xdc);

// return success
return(1);
} // end Draw_Text_GDI

///////////////////////////////////////////////////////////////////


int Set_Palette_Entry(int color_index, LPPALETTEENTRY color)
{
// this function sets a palette color in the palette
lpddpal->SetEntries(0,color_index,1,color);

// set data in shadow palette
memcpy(&palette[color_index],color,sizeof(PALETTEENTRY));

// return success
return(1);
} // end Set_Palette_Entry

///////////////////////////////////////////////////////////

int Translate_Polygon2D(POLYGON2D_PTR poly, int dx, int dy)
{
// this function translates the center of a polygon

// test for valid pointer
if (!poly)
   return(0);

// translate
poly->x0+=dx;
poly->y0+=dy;

// return success
return(1);

} // end Translate_Polygon2D

///////////////////////////////////////////////////////////////

int Rotate_Polygon2D(POLYGON2D_PTR poly, int theta)
{
// this function rotates the local coordinates of the polygon

// test for valid pointer
if (!poly)
   return(0);

// loop and rotate each point, very crude, no lookup!!!
for (int curr_vert = 0; curr_vert < poly->num_verts; curr_vert++)
    {

    // perform rotation
    float xr = (float)poly->vlist[curr_vert].x*cos_look[theta] - 
                    (float)poly->vlist[curr_vert].y*sin_look[theta];