TempleOSCDV4.11.ISO

Demo/Graphics/Cartesian.HC

@@ -0,0 +1,48 @@
+//x must be global.
+//Might as well make y global.
+
+F64 x,y,y_last;
+
+U0 Cartesian()
+{
+  U8 *st;
+  I64 ch=0,h,v;
+  Bool first;
+  CDC *dc=DCAlias;
+  do {
+    DocClear;
+    "Enter algebraic equation to graph.\n"
+	  "Example: y=2*x\n"
+	  "y=";
+    if (st=GetStr) {
+      if (*st) {
+	h=Fs->pix_width/2;
+	v=Fs->pix_height/2;
+	dc->color=RED;
+	GrLine(dc,h,0,h,2*v+1);
+	GrLine(dc,0,v,2*h+1,v);
+	first=TRUE;
+	dc->color=BLACK;
+	for (x=-h;x<=h;x++) {
+	  y=-ExePrint("ToF64(%s);",st)(F64);
+	  if (!first)
+	    GrLine(dc,x-1+h,y_last+v,x+h,y+v);
+	  y_last=y;
+	  first=FALSE;
+	}
+	ch=GetChar;
+      } else
+	ch=CH_SHIFT_ESC;
+      Free(st);
+    } else
+      ch=CH_SHIFT_ESC;
+    DCFill;
+  } while (ch!=CH_SHIFT_ESC && ch!=CH_ESC);
+  DCDel(dc);
+}
+
+Cartesian;
+
+//For better performance, compile the expression entered by the
+//user one time with $LK,"LexExpression2Bin",A="MN:LexExpression2Bin"$() and use $LK,"Call",A="MN:Call"$().
+//See $LK,"::/Demo/CompileDemo.HC"$.