📄 demo8_9.cpp
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} // end if
} // end if
else
{
// increment edge 1 on X and edge 2 on Y:
count1=xdiff1; // count for X increment on edge 1
count2=ydiff2; // count for Y increment on edge 2
while (count1 && count2)
{ // continue drawing until one edge is done
// calculate edge 1:
while ((errorterm1 < xdiff1) && (count1 > 0))
{ // finished w/edge 1?
if (count1--)
{
// count down on edge 1
offset1+=xunit1; // increment pixel offset
xstart1+=xunit1;
} // end if
errorterm1+=ydiff1; // increment error term
if (errorterm1 < xdiff1)
{ // If not more than XDIFF
vbuffer[offset1]=(UCHAR)poly->color; // ...plot a pixel
} // end if
} // end while
errorterm1-=xdiff1; // If time to increment X, restore error term
// calculate edge 2:
errorterm2+=xdiff2; // increment error term
if (errorterm2 >= ydiff2)
{ // if time to increment Y...
errorterm2-=ydiff2; // ...restore error term
offset2+=xunit2; // ...and advance offset to next pixel
xstart2+=xunit2;
} // end if
count2--;
// draw line from edge 1 to edge 2:
length=offset2-offset1; // determine length of horizontal line
if (length < 0)
{ // if negative...
length=-length; // ...make it positive
start=offset2; // and set START to edge 2
} // end if
else
start=offset1; // else set START to edge 1
for (int index=start; index < start+length+1; index++) // from edge to edge
{
vbuffer[index]=(UCHAR)poly->color; // ...draw the line
} // end for index
offset1+=mempitch; // advance edge 1 offset to next line
ystart1++;
offset2+=mempitch; // advance edge 2 offset to next line
ystart2++;
} // end while
} // end if
} // end if
else
{
if (xdiff2 > ydiff2)
{
// increment edge 1 on Y and edge 2 on X:
count1=ydiff1; // count for Y increment on edge 1
count2=xdiff2; // count for X increment on edge 2
while(count1 && count2)
{ // continue drawing until one edge is done
// calculate edge 1:
errorterm1+=xdiff1; // Increment error term
if (errorterm1 >= ydiff1)
{ // if time to increment Y...
errorterm1-=ydiff1; // ...restore error term
offset1+=xunit1; // ...and advance offset to next pixel
xstart1+=xunit1;
} // end if
count1--;
// Calculate edge 2:
while ((errorterm2 < xdiff2) && (count2 > 0))
{ // finished w/edge 1?
if (count2--)
{ // count down on edge 2
offset2+=xunit2; // increment pixel offset
xstart2+=xunit2;
} // end if
errorterm2+=ydiff2; // increment error term
if (errorterm2 < xdiff2)
{ // if not more than XDIFF
vbuffer[offset2]=(UCHAR)poly->color; // ...plot a pixel
} // end if
} // end while
errorterm2-=xdiff2; // if time to increment X, restore error term
// draw line from edge 1 to edge 2:
length=offset2-offset1; // determine length of horizontal line
if (length < 0)
{ // if negative...
length=-length; // ...make it positive
start=offset2; // and set START to edge 2
} // end if
else
start=offset1; // else set START to edge 1
for (int index=start; index < start+length+1; index++) // from edge to edge...
{
vbuffer[index]=(UCHAR)poly->color; // ...draw the line
} // end for index
offset1+=mempitch; // advance edge 1 offset to next line
ystart1++;
offset2+=mempitch; // advance edge 2 offset to next line
ystart2++;
} // end if
} // end if
else
{
// increment edge 1 on Y and edge 2 on Y:
count1=ydiff1; // count for Y increment on edge 1
count2=ydiff2; // count for Y increment on edge 2
while(count1 && count2)
{
// continue drawing until one edge is done
// calculate edge 1:
errorterm1+=xdiff1; // increment error term
if (errorterm1 >= ydiff1)
{ // if time to increment Y
errorterm1-=ydiff1; // ...restore error term
offset1+=xunit1; // ...and advance offset to next pixel
xstart1+=xunit1;
} // end if
count1--;
// calculate edge 2:
errorterm2+=xdiff2; // increment error term
if (errorterm2 >= ydiff2)
{ // if time to increment Y
errorterm2-=ydiff2; // ...restore error term
offset2+=xunit2; // ...and advance offset to next pixel
xstart2+=xunit2;
} // end if
--count2;
// draw line from edge 1 to edge 2:
length=offset2-offset1; // determine length of horizontal line
if (length < 0)
{
// if negative...
length=-length; // ...make it positive
start=offset2; // and set START to edge 2
} // end if
else
start=offset1; // else set START to edge 1
for (int index=start; index < start+length+1; index++)
{ // from edge to edge
vbuffer[index]=(UCHAR)poly->color; // ...draw the linee
} // end for index
offset1+=mempitch; // advance edge 1 offset to next line
ystart1++;
offset2+=mempitch; // advance edge 2 offset to next line
ystart2++;
} // end while
} // end else
} // end if
// another edge (at least) is complete. Start next edge, if any.
if (!count1)
{ // if edge 1 is complete...
--edgecount; // decrement the edge count
startvert1=endvert1; // make ending vertex into start vertex
--endvert1; // and get new ending vertex
if (endvert1 < 0)
endvert1=poly->num_verts-1; // check for wrap
xend1=poly->vlist[endvert1].x+poly->x0; // get x & y of new end vertex
yend1=poly->vlist[endvert1].y+poly->y0;
} // end if
if (!count2)
{ // if edge 2 is complete...
--edgecount; // decrement the edge count
startvert2=endvert2; // make ending vertex into start vertex
endvert2++; // and get new ending vertex
if (endvert2==(poly->num_verts))
endvert2=0; // check for wrap
xend2=poly->vlist[endvert2].x+poly->x0; // get x & y of new end vertex
yend2=poly->vlist[endvert2].y+poly->y0;
} // end if
} // end while
} // end Draw_Filled_Polygon2D
///////////////////////////////////////////////////////////////
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];
float yr = (float)poly->vlist[curr_vert].x*sin_look[theta] +
(float)poly->vlist[curr_vert].y*cos_look[theta];
// store result back
poly->vlist[curr_vert].x = xr;
poly->vlist[curr_vert].y = yr;
} // end for curr_vert
// return success
return(1);
} // end Rotate_Polygon2D
////////////////////////////////////////////////////////
int Scale_Polygon2D(POLYGON2D_PTR poly, float sx, float sy)
{
// this function scalesthe local coordinates of the polygon
// test for valid pointer
if (!poly)
return(0);
// loop and scale each point
for (int curr_vert = 0; curr_vert < poly->num_verts; curr_vert++)
{
// scale and store result back
poly->vlist[curr_vert].x *= sx;
poly->vlist[curr_vert].y *= sy;
} // end for curr_vert
// return success
return(1);
} // end Scale_Polygon2D
///////////////////////////////////////////////////////////
inline int Draw_Pixel(int x, int y,int color,
UCHAR *video_buffer, int lpitch)
{
// this function plots a single pixel at x,y with color
video_buffer[x + y*lpitch] = color;
// return success
return(1);
} // end Draw_Pixel
/////////////////////////////////////////////////////////////
int DDraw_Fill_Surface(LPDIRECTDRAWSURFACE4 lpdds,int color)
{
DDBLTFX ddbltfx; // this contains the DDBLTFX structure
// clear out the structure and set the size field
DDRAW_INIT_STRUCT(ddbltfx);
// set the dwfillcolor field to the desired color
ddbltfx.dwFillColor = color;
// ready to blt to surface
lpdds->Blt(NULL, // ptr to dest rectangle
NULL, // ptr to source surface, NA
NULL, // ptr to source rectangle, NA
DDBLT_COLORFILL | DDBLT_WAIT, // fill and wait
&ddbltfx); // ptr to DDBLTFX structure
// return success
return(1);
} // end DDraw_Fill_Surface
///////////////////////////////////////////////////////////////
LRESULT CALLBACK WindowProc(HWND hwnd,
UINT msg,
WPARAM wparam,
LPARAM lparam)
{
// this is the main message handler of the system
PAINTSTRUCT ps; // used in WM_PAINT
HDC hdc; // handle to a device context
char buffer[80]; // used to print strings
// what is the message
switch(msg)
{
case WM_CREATE:
{
// do initialization stuff here
// return success
return(0);
} break;
case WM_PAINT:
{
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