Basic Fan

fan.c

+/**
+ * rotating fan
+ */
+#include <graphics.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+
+double rotatex(double x, double y, double angle, double pivotx, double pivoty){
+    return (x)*cos(angle) - (y)*sin(angle) + pivotx* (1-cos(angle)) + pivoty*(sin(angle));
+    // return (x - pivotx)*cos(angle) - (y - pivoty)*sin(angle) + pivotx;
+}
+double rotatey(double x, double y, double angle, double pivotx, double pivoty){
+    return (x)*sin(angle) + (y)*cos(angle) + pivoty* (1-cos(angle)) - pivotx*(sin(angle));
+    // return (x - pivotx)*sin(angle) - (y - pivoty)*cos(angle) + pivoty;
+}
+
+int kbhit()
+{
+    struct timeval tv;
+    fd_set fds;
+    tv.tv_sec = 0;
+    tv.tv_usec = 0;
+    FD_ZERO(&fds);
+    FD_SET(STDIN_FILENO, &fds); //STDIN_FILENO is 0
+    select(STDIN_FILENO+1, &fds, NULL, NULL, &tv);
+    return FD_ISSET(STDIN_FILENO, &fds);
+}
+
+int main()
+{
+
+    /* request autodetection */
+    int gdriver = DETECT, gmode, errorcode;
+    /* Local Variables */
+    double cx, cy;
+    double l1x1, l1y1, l1x2, l1y2;
+    double l1angle = 120 / 180.0 * 3.14;
+    double l2angle = 240 / 180.0 * 3.14;
+    double rotate_angle = 2 / 180.0 * 3.14;
+    int speed=1;
+    int i=0;
+
+    /* initialize graphics and local variables */
+    initgraph(&gdriver, &gmode, "");
+
+    cx = getmaxx() / 2;
+    cy = getmaxy() / 2;
+
+    l1x1 = cx;
+    l1y1 = cy - 20;
+    l1x2 = cx;
+    l1y2 = cy - 90;
+
+    while (!kbhit()) {
+        i++;
+        if(i>=60){
+            l1x1 = cx;
+            l1y1 = cy - 20;
+            l1x2 = cx;
+            l1y2 = cy - 90;
+            i=0;
+
+        }
+
+        circle((int)cx, (int)cy, 20);
+        line((int)l1x1, (int)l1y1, (int)l1x2,(int) l1y2);
+
+        line(
+            (int)rotatex(l1x1, l1y1, l1angle, cx, cy),
+            (int)rotatey(l1x1, l1y1, l1angle, cx, cy),
+            (int)rotatex(l1x2, l1y2, l1angle, cx, cy),
+            (int)rotatey(l1x2, l1y2, l1angle, cx, cy)
+        );
+
+        line(
+            (int)rotatex(l1x1, l1y1, l2angle, cx, cy),
+            (int)rotatey(l1x1, l1y1, l2angle, cx, cy),
+            (int)rotatex(l1x2, l1y2, l2angle, cx, cy),
+            (int)rotatey(l1x2, l1y2, l2angle, cx, cy)
+        );
+
+        /* prepare for next  frame */
+        delay(15);
+        cleardevice();
+
+        l1x1 = rotatex(l1x1, l1y1, rotate_angle, cx, cy);
+        l1y1 = rotatey(l1x1, l1y1, rotate_angle, cx, cy);
+        l1x2 = rotatex(l1x2, l1y2, rotate_angle, cx, cy);
+        l1y2 = rotatey(l1x2, l1y2, rotate_angle, cx, cy);
+
+    }
+
+    /* clean up */
+    closegraph();
+    return 0;
+}