?? t3dlib1.cpp
字號:
// unlock the primary surface
lpddsprimary->Unlock(NULL);
// reset the primary surface
primary_buffer = NULL;
primary_lpitch = 0;
// return success
return(1);
} // end DDraw_Unlock_Primary_Surface
//////////////////////////////////////////////////////////
UCHAR *DDraw_Lock_Back_Surface(void)
{
// this function locks the secondary back surface and returns a pointer to it
// and updates the global variables secondary buffer, and back_lpitch
// is this surface already locked
if (back_buffer)
{
// return to current lock
return(back_buffer);
} // end if
// lock the primary surface
DDRAW_INIT_STRUCT(ddsd);
lpddsback->Lock(NULL,&ddsd,DDLOCK_WAIT | DDLOCK_SURFACEMEMORYPTR,NULL);
// set globals
back_buffer = (UCHAR *)ddsd.lpSurface;
back_lpitch = ddsd.lPitch;
// return pointer to surface
return(back_buffer);
} // end DDraw_Lock_Back_Surface
///////////////////////////////////////////////////////////
int DDraw_Unlock_Back_Surface(void)
{
// this unlocks the secondary
// is this surface valid
if (!back_buffer)
return(0);
// unlock the secondary surface
lpddsback->Unlock(NULL);
// reset the secondary surface
back_buffer = NULL;
back_lpitch = 0;
// return success
return(1);
} // end DDraw_Unlock_Back_Surface
///////////////////////////////////////////////////////////
DWORD Get_Clock(void)
{
// this function returns the current tick count
// return time
return(GetTickCount());
} // end Get_Clock
///////////////////////////////////////////////////////////
DWORD Start_Clock(void)
{
// this function starts the clock, that is, saves the current
// count, use in conjunction with Wait_Clock()
return(start_clock_count = Get_Clock());
} // end Start_Clock
////////////////////////////////////////////////////////////
DWORD Wait_Clock(DWORD count)
{
// this function is used to wait for a specific number of clicks
// since the call to Start_Clock
while((Get_Clock() - start_clock_count) < count);
return(Get_Clock());
} // end Wait_Clock
///////////////////////////////////////////////////////////
int Draw_Clip_Line16(int x0,int y0, int x1, int y1, int color,
UCHAR *dest_buffer, int lpitch)
{
// this function draws a clipped line
int cxs, cys,
cxe, cye;
// clip and draw each line
cxs = x0;
cys = y0;
cxe = x1;
cye = y1;
// clip the line
if (Clip_Line(cxs,cys,cxe,cye))
Draw_Line16(cxs, cys, cxe,cye,color,dest_buffer,lpitch);
// return success
return(1);
} // end Draw_Clip_Line16
///////////////////////////////////////////////////////////
int Draw_Clip_Line(int x0,int y0, int x1, int y1, int color,
UCHAR *dest_buffer, int lpitch)
{
// this function draws a wireframe triangle
int cxs, cys,
cxe, cye;
// clip and draw each line
cxs = x0;
cys = y0;
cxe = x1;
cye = y1;
// clip the line
if (Clip_Line(cxs,cys,cxe,cye))
Draw_Line(cxs, cys, cxe,cye,color,dest_buffer,lpitch);
// return success
return(1);
} // end Draw_Clip_Line
///////////////////////////////////////////////////////////
int Clip_Line(int &x1,int &y1,int &x2, int &y2)
{
// this function clips the sent line using the globally defined clipping
// region
// internal clipping codes
#define CLIP_CODE_C 0x0000
#define CLIP_CODE_N 0x0008
#define CLIP_CODE_S 0x0004
#define CLIP_CODE_E 0x0002
#define CLIP_CODE_W 0x0001
#define CLIP_CODE_NE 0x000a
#define CLIP_CODE_SE 0x0006
#define CLIP_CODE_NW 0x0009
#define CLIP_CODE_SW 0x0005
int xc1=x1,
yc1=y1,
xc2=x2,
yc2=y2;
int p1_code=0,
p2_code=0;
// determine codes for p1 and p2
if (y1 < min_clip_y)
p1_code|=CLIP_CODE_N;
else
if (y1 > max_clip_y)
p1_code|=CLIP_CODE_S;
if (x1 < min_clip_x)
p1_code|=CLIP_CODE_W;
else
if (x1 > max_clip_x)
p1_code|=CLIP_CODE_E;
if (y2 < min_clip_y)
p2_code|=CLIP_CODE_N;
else
if (y2 > max_clip_y)
p2_code|=CLIP_CODE_S;
if (x2 < min_clip_x)
p2_code|=CLIP_CODE_W;
else
if (x2 > max_clip_x)
p2_code|=CLIP_CODE_E;
// try and trivially reject
if ((p1_code & p2_code))
return(0);
// test for totally visible, if so leave points untouched
if (p1_code==0 && p2_code==0)
return(1);
// determine end clip point for p1
switch(p1_code)
{
case CLIP_CODE_C: break;
case CLIP_CODE_N:
{
yc1 = min_clip_y;
xc1 = x1 + 0.5+(min_clip_y-y1)*(x2-x1)/(y2-y1);
} break;
case CLIP_CODE_S:
{
yc1 = max_clip_y;
xc1 = x1 + 0.5+(max_clip_y-y1)*(x2-x1)/(y2-y1);
} break;
case CLIP_CODE_W:
{
xc1 = min_clip_x;
yc1 = y1 + 0.5+(min_clip_x-x1)*(y2-y1)/(x2-x1);
} break;
case CLIP_CODE_E:
{
xc1 = max_clip_x;
yc1 = y1 + 0.5+(max_clip_x-x1)*(y2-y1)/(x2-x1);
} break;
// these cases are more complex, must compute 2 intersections
case CLIP_CODE_NE:
{
// north hline intersection
yc1 = min_clip_y;
xc1 = x1 + 0.5+(min_clip_y-y1)*(x2-x1)/(y2-y1);
// test if intersection is valid, of so then done, else compute next
if (xc1 < min_clip_x || xc1 > max_clip_x)
{
// east vline intersection
xc1 = max_clip_x;
yc1 = y1 + 0.5+(max_clip_x-x1)*(y2-y1)/(x2-x1);
} // end if
} break;
case CLIP_CODE_SE:
{
// south hline intersection
yc1 = max_clip_y;
xc1 = x1 + 0.5+(max_clip_y-y1)*(x2-x1)/(y2-y1);
// test if intersection is valid, of so then done, else compute next
if (xc1 < min_clip_x || xc1 > max_clip_x)
{
// east vline intersection
xc1 = max_clip_x;
yc1 = y1 + 0.5+(max_clip_x-x1)*(y2-y1)/(x2-x1);
} // end if
} break;
case CLIP_CODE_NW:
{
// north hline intersection
yc1 = min_clip_y;
xc1 = x1 + 0.5+(min_clip_y-y1)*(x2-x1)/(y2-y1);
// test if intersection is valid, of so then done, else compute next
if (xc1 < min_clip_x || xc1 > max_clip_x)
{
xc1 = min_clip_x;
yc1 = y1 + 0.5+(min_clip_x-x1)*(y2-y1)/(x2-x1);
} // end if
} break;
case CLIP_CODE_SW:
{
// south hline intersection
yc1 = max_clip_y;
xc1 = x1 + 0.5+(max_clip_y-y1)*(x2-x1)/(y2-y1);
// test if intersection is valid, of so then done, else compute next
if (xc1 < min_clip_x || xc1 > max_clip_x)
{
xc1 = min_clip_x;
yc1 = y1 + 0.5+(min_clip_x-x1)*(y2-y1)/(x2-x1);
} // end if
} break;
default:break;
} // end switch
// determine clip point for p2
switch(p2_code)
{
case CLIP_CODE_C: break;
case CLIP_CODE_N:
{
yc2 = min_clip_y;
xc2 = x2 + (min_clip_y-y2)*(x1-x2)/(y1-y2);
} break;
case CLIP_CODE_S:
{
yc2 = max_clip_y;
xc2 = x2 + (max_clip_y-y2)*(x1-x2)/(y1-y2);
} break;
case CLIP_CODE_W:
{
xc2 = min_clip_x;
yc2 = y2 + (min_clip_x-x2)*(y1-y2)/(x1-x2);
} break;
case CLIP_CODE_E:
{
xc2 = max_clip_x;
yc2 = y2 + (max_clip_x-x2)*(y1-y2)/(x1-x2);
} break;
// these cases are more complex, must compute 2 intersections
case CLIP_CODE_NE:
{
// north hline intersection
yc2 = min_clip_y;
xc2 = x2 + 0.5+(min_clip_y-y2)*(x1-x2)/(y1-y2);
// test if intersection is valid, of so then done, else compute next
if (xc2 < min_clip_x || xc2 > max_clip_x)
{
// east vline intersection
xc2 = max_clip_x;
yc2 = y2 + 0.5+(max_clip_x-x2)*(y1-y2)/(x1-x2);
} // end if
} break;
case CLIP_CODE_SE:
{
// south hline intersection
yc2 = max_clip_y;
xc2 = x2 + 0.5+(max_clip_y-y2)*(x1-x2)/(y1-y2);
// test if intersection is valid, of so then done, else compute next
if (xc2 < min_clip_x || xc2 > max_clip_x)
{
// east vline intersection
xc2 = max_clip_x;
yc2 = y2 + 0.5+(max_clip_x-x2)*(y1-y2)/(x1-x2);
} // end if
} break;
case CLIP_CODE_NW:
{
// north hline intersection
yc2 = min_clip_y;
xc2 = x2 + 0.5+(min_clip_y-y2)*(x1-x2)/(y1-y2);
// test if intersection is valid, of so then done, else compute next
if (xc2 < min_clip_x || xc2 > max_clip_x)
{
xc2 = min_clip_x;
yc2 = y2 + 0.5+(min_clip_x-x2)*(y1-y2)/(x1-x2);
} // end if
} break;
case CLIP_CODE_SW:
{
// south hline intersection
yc2 = max_clip_y;
xc2 = x2 + 0.5+(max_clip_y-y2)*(x1-x2)/(y1-y2);
// test if intersection is valid, of so then done, else compute next
if (xc2 < min_clip_x || xc2 > max_clip_x)
{
xc2 = min_clip_x;
yc2 = y2 + 0.5+(min_clip_x-x2)*(y1-y2)/(x1-x2);
} // end if
} break;
default:break;
} // end switch
// do bounds check
if ((xc1 < min_clip_x) || (xc1 > max_clip_x) ||
(yc1 < min_clip_y) || (yc1 > max_clip_y) ||
(xc2 < min_clip_x) || (xc2 > max_clip_x) ||
(yc2 < min_clip_y) || (yc2 > max_clip_y) )
{
return(0);
} // end if
// store vars back
x1 = xc1;
y1 = yc1;
x2 = xc2;
y2 = yc2;
return(1);
} // end Clip_Line
///////////////////////////////////////////////////////////
int Draw_Line(int x0, int y0, // starting position
int x1, int y1, // ending position
int color, // color index
UCHAR *vb_start, int lpitch) // video buffer and memory pitch
{
// this function draws a line from xo,yo to x1,y1 using differential error
// terms (based on Bresenahams work)
int dx, // difference in x's
dy, // difference in y's
dx2, // dx,dy * 2
dy2,
x_inc, // amount in pixel space to move during drawing
y_inc, // amount in pixel space to move during drawing
error, // the discriminant i.e. error i.e. decision variable
index; // used for looping
// pre-compute first pixel address in video buffer
vb_start = vb_start + x0 + y0*lpitch;
// compute horizontal and vertical deltas
dx = x1-x0;
dy = y1-y0;
// test which direction the line is going in i.e. slope angle
if (dx>=0)
{
x_inc = 1;
} // end if line is moving right
else
{
x_inc = -1;
dx = -dx; // need absolute value
} // end else moving left
// test y component of slope
if (dy>=0)
{
y_inc = lpitch;
} // end if line is moving down
else
{
y_inc = -lpitch;
dy = -dy; // need absolute value
} // end else moving up
// compute (dx,dy) * 2
dx2 = dx << 1;
dy2 = dy << 1;
// now based on which delta is greater we can draw the line
if (dx > dy)
{
// initialize error term
error = dy2 - dx;
// draw the line
for (index=0; index <= dx; index++)
{
// set the pixel
*vb_start = color;
// test if error has overflowed
if (error >= 0)
{
error-=dx2;
// move to next line
vb_start+=y_inc;
} // end if error overflowed
?? 快捷鍵說明
復制代碼
Ctrl + C
搜索代碼
Ctrl + F
全屏模式
F11
切換主題
Ctrl + Shift + D
顯示快捷鍵
?
增大字號
Ctrl + =
減小字號
Ctrl + -