#include <windows.h>
#include <math.h>
// シンプル円描画（小数切捨て方式）
void ReallySimpleCircle (HDC hdc, LONG radius, POINT center, COLORREF col){
LONG cx = 0, cy;
double xLimit = sqrt ((double) (radius * radius)
/ 2); // r*r*√2 → 45°
while (cx++ <= xLimit){
cy = (LONG) floor (sqrt (radius
* radius - cx * cx));
SetPixel (hdc, cx + center.x,
cy + center.y, col); // 45-90
度の間
SetPixel (hdc, cx + center.x,
-cy + center.y, col); // 270-315 度の間
SetPixel (hdc, -cx + center.x,
cy + center.y, col); // 90-135 度の間
SetPixel (hdc, -cx + center.x,
-cy + center.y, col); // 225-270 度の間
SetPixel (hdc, cy + center.x,
cx + center.y, col); // 0-45
度の間
SetPixel (hdc, cy + center.x,
-cx + center.y, col); // 315-360 度の間
SetPixel (hdc, -cy + center.x,
cx + center.y, col); // 135-180 度の間
SetPixel (hdc, -cy + center.x,
-cx + center.y, col); // 180-225 度の間
}
}
// シンプル円描画２（値のより近いピクセルを選択する方式）
void ReallySimpleCircle2 (HDC hdc, LONG radius, POINT center, COLORREF
col){
LONG cx = 0, cy=radius;
double xLimit = sqrt ((double) (radius *
radius) / 2); // 45度→r*√２
double d1, d2;
for (cx=0; cx <= xLimit ; cx++)
{
d1 = (cx * cx+cy*cy) - radius
* radius;
d2 = (cx * cx+(cy-1)*(cy-1))
- radius * radius;
if (abs(d1)>abs(d2)) cy--;
SetPixel (hdc, cx + center.x,
cy + center.y, col); // 45-90
度の間
SetPixel (hdc, cx + center.x,
-cy + center.y, col); // 270-315 度の間
SetPixel (hdc, -cx + center.x,
cy + center.y, col); // 90-135 度の間
SetPixel (hdc, -cx + center.x,
-cy + center.y, col); // 225-270 度の間
SetPixel (hdc, cy + center.x,
cx + center.y, col); // 0-45
度の間
SetPixel (hdc, cy + center.x,
-cx + center.y, col); // 315-360 度の間
SetPixel (hdc, -cy + center.x,
cx + center.y, col); // 135-180 度の間
SetPixel (hdc, -cy + center.x,
-cx + center.y, col); // 180-225 度の間
}
}
// Win32API GDI 円描画
void Win32APIGDICircle (HDC hdc, LONG radius, POINT center){
SelectObject (hdc, GetStockObject (NULL_BRUSH));
Ellipse (hdc,
center.x - radius,
center.y + radius,
center.x + radius,
center.y - radius);
}
// ブレゼンハム(Bresenham)の円描画 （旧版）
void BresenhamCircle (HDC hdc, LONG radius, POINT center, COLORREF col){
LONG cx, cy, d;
cx = 0;
cy = radius;
d = 2 - 2 * radius;
// 初期座標をあらかじめ描画する
SetPixel (hdc, cx + center.x, cy + center.y, col);
// 座標 (0, R);
SetPixel (hdc, cx + center.x, -cy + center.y, col);
// 座標 (0, -R);
SetPixel (hdc, cy + center.x, cx + center.y, col);
// 座標 (R, 0);
SetPixel (hdc, -cy + center.x, cx + center.y, col);
// 座標 (-R, 0);
while (1){
if (d > -cy){
--cy;
d +=
1 - 2 * cy;
}
if (d <= cx){
++cx;
d +=
1 + 2 * cx;
}
if (!cy) return;
// 描画終了
// 描画
SetPixel (hdc, cx + center.x,
cy + center.y, col); // 0-90
度の間
SetPixel (hdc, -cx + center.x,
cy + center.y, col); // 90-180 度の間
SetPixel (hdc, -cx + center.x,
-cy + center.y, col); // 180-270 度の間
SetPixel (hdc, cx + center.x,
-cy + center.y, col); // 270-360 度の間
}
}
// ミッチェナー(Miechener) の円描画
void MiechenerCircle (HDC hdc, LONG radius, POINT center, COLORREF col){
LONG cx, cy, d;
d = 3 - 2 * radius;
cy = radius;
// 初期座標をあらかじめ描画する
SetPixel (hdc, center.x, radius + center.y, col);
// 座標 (0, R);
SetPixel (hdc, center.x, -radius + center.y, col);
// 座標 (0, -R);
SetPixel (hdc, radius + center.x, center.y, col);
// 座標 (R, 0);
SetPixel (hdc, -radius + center.x, center.y, col);
// 座標 (-R, 0);
for (cx = 0; cx <= cy; cx++){
if (d >= 0) {
d +=
10 + 4 * cx - 4 * cy;
cy--;
}
else {
d +=
6 + 4 * cx;
}
// 描画
SetPixel (hdc, cy + center.x,
cx + center.y, col); // 0-45
度の間
SetPixel (hdc, cx + center.x,
cy + center.y, col); // 45-90
度の間
SetPixel (hdc, -cx + center.x,
cy + center.y, col); // 90-135 度の間
SetPixel (hdc, -cy + center.x,
cx + center.y, col); // 135-180 度の間
SetPixel (hdc, -cy + center.x,
-cx + center.y, col); // 180-225 度の間
SetPixel (hdc, -cx + center.x,
-cy + center.y, col); // 225-270 度の間
SetPixel (hdc, cx + center.x,
-cy + center.y, col); // 270-315 度の間
SetPixel (hdc, cy + center.x,
-cx + center.y, col); // 315-360 度の間
}
}
// ブレゼンハム(Bresenham)の中点分岐の円描画
void MidpointCircle (HDC hdc, LONG radius, POINT center, COLORREF col){
LONG cx, cy, d, dH, dD;
d = 1 - radius;
dH = 3;
dD = 5 - 2 * radius;
cy = radius;
// drawing the circle:
for (cx = 0; cx <= cy; cx++){
if (d < 0){
d
+= dH;
dH
+= 2;
dD
+= 2;
}
else{
d
+= dD;
dH
+= 2;
dD
+= 4;
--cy;
}
// 描画
SetPixel (hdc, cy + center.x,
cx + center.y, col); // 0-45
度の間
SetPixel (hdc, cx + center.x,
cy + center.y, col); // 45-90
度の間
SetPixel (hdc, -cx + center.x,
cy + center.y, col); // 90-135 度の間
SetPixel (hdc, -cy + center.x,
cx + center.y, col); // 135-180 度の間
SetPixel (hdc, -cy + center.x,
-cx + center.y, col); // 180-225 度の間
SetPixel (hdc, -cx + center.x,
-cy + center.y, col); // 225-270 度の間
SetPixel (hdc, cx + center.x,
-cy + center.y, col); // 270-315 度の間
SetPixel (hdc, cy + center.x,
-cx + center.y, col); // 315-360 度の間
}
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM
lParam){
RECT rc;
static POINT center;
HDC
hdc;
PAINTSTRUCT ps;
int RADIUS = 100;
switch (message){
case WM_SIZE:
InvalidateRect(hwnd, NULL, TRUE);
break;
case WM_PAINT:
GetClientRect(hwnd, &rc);
center.x = rc.right/ 2;
center.y = rc.bottom/ 2;
hdc = BeginPaint (hwnd, &ps);
// 中心線描画（水平）
MoveToEx (hdc, 0, center.y,
NULL);
LineTo (hdc, rc.right, center.y);
// 中心線描画（垂直）
MoveToEx (hdc, center.x, 0,
NULL);
LineTo (hdc, center.x, rc.bottom);
// シンプル円描画(小数切捨て)
ReallySimpleCircle (hdc, RADIUS,
center, RGB(255, 0, 0));
// シンプル円描画(値のより近いピクセルを選択する方式)
center.x += 20;
ReallySimpleCircle2 (hdc, RADIUS,
center, RGB(0, 255, 0));
// Win32API GDI 円描画
center.x += 20;
Win32APIGDICircle (hdc, RADIUS,
center);
// ブレゼンハム(Bresenham)の円描画 （旧版）
center.x += 20;
BresenhamCircle (hdc, RADIUS,
center, RGB(255, 0, 255));
// ミッチェナー(Miechener) の円描画
center.x += 20;
MiechenerCircle (hdc, RADIUS,
center, RGB(0, 0, 255));
// ブレゼンハム(Bresenham)の中点分岐の円描画
center.x += 20;
MidpointCircle (hdc, RADIUS,
center, RGB(0, 100, 100));
EndPaint (hwnd, &ps);
break;
case WM_DESTROY:
PostQuitMessage (0);
break;
}
return DefWindowProc (hwnd, message, wParam, lParam);
}
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR
lpCmdLine, int iCmdShow){
static TCHAR szAppName[] = TEXT ("CircleDemoApp");
HWND hwnd;
MSG
msg;
WNDCLASS wndclass;
wndclass.style
= CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon
= LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor
= LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject
(WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = szAppName;
if (!RegisterClass (&wndclass)){
MessageBox (NULL, TEXT
("This program requires Windows NT!"), szAppName, MB_ICONERROR)
;
return 0 ;
}
hwnd = CreateWindow (szAppName, TEXT("円描画の比較(Comparing
Circle Drawings)"),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, 500, 300,
NULL, NULL, hInstance, NULL);
ShowWindow (hwnd, iCmdShow);
UpdateWindow (hwnd);
while (GetMessage (&msg, NULL, 0, 0)){
TranslateMessage (&msg);
DispatchMessage (&msg);
}
return msg.wParam;
}
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