From 8b08533e3536d08d3d733aa424069f9a8d10300c Mon Sep 17 00:00:00 2001
From: Ian C <ianc@noddybox.co.uk>
Date: Tue, 23 Oct 2018 14:35:41 +0000
Subject: Added road demo.

---
 xd.c | 238 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 235 insertions(+), 3 deletions(-)

(limited to 'xd.c')

diff --git a/xd.c b/xd.c
index 9f7a037..44a2ef0 100644
--- a/xd.c
+++ b/xd.c
@@ -173,10 +173,11 @@ static void	FollowDemo(void);
 static void	CatwalkDemo(void);
 static void	GravityDemo(void);
 static void	SnowDemo(void);
+static void	RoadDemo(void);
 
 /* ---------------------------------------- GLOBAL VARS
 */
-#define NO_DEMOS	19
+#define NO_DEMOS	20
 
 static int		demo=NO_DEMOS-1;
 
@@ -279,6 +280,11 @@ static DemoInfo		demotbl[NO_DEMOS]=
 				SnowDemo,
 				UsesPixmap
 			    },
+			    {
+				"Road Demo",
+				RoadDemo,
+				UsesPixmap
+			    },
 			};
 
 /* ---------------------------------------- X11 VARS
@@ -304,6 +310,7 @@ static unsigned long		blue;
 static int			mouse_x;
 static int			mouse_y;
 static unsigned int		mouse_b;
+static KeySym			last_key = XK_VoidSymbol;
 
 static double			sintab[3600];
 static double			costab[3600];
@@ -448,6 +455,10 @@ int main(int argc, char *argv[])
 		    HandleKey(&ev.xkey);
 		    break;
 
+		case KeyRelease:
+		    last_key = XK_VoidSymbol;
+		    break;
+
 		/*
 		case ButtonPress:
 		    HandleMouse(ev.xbutton.x,ev.xbutton.y,
@@ -537,6 +548,13 @@ static void Bounce(int *x, int *y, int *ix, int *iy)
     }
 }
 
+static double SgnF(double a)
+{
+    if (a < 0.0) return -1.0;
+    if (a > 0.0) return 1.0;
+    return 0.0;
+}
+
 
 /* ---------------------------------------- X11 UTILS
 */
@@ -599,7 +617,7 @@ static void OpenX(void)
 	 KeyPressMask|ButtonPressMask|ButtonReleaseMask|
 	 	PointerMotionMask|ExposureMask);
     */
-    XSelectInput(disp,win,KeyPressMask);
+    XSelectInput(disp,win,KeyPressMask|KeyReleaseMask);
 
     XStoreName(disp,win,demotbl[demo].name);
 
@@ -812,7 +830,9 @@ static void SetCol(unsigned long col)
 
 static void HandleKey(XKeyEvent *key)
 {
-    switch(XLookupKeysym(key,0))
+    KeySym sym;
+
+    switch((sym = XLookupKeysym(key,0)))
     {
 	case XK_Prior:
 	    demo--;
@@ -834,6 +854,7 @@ static void HandleKey(XKeyEvent *key)
 	    break;
 
 	default:
+	    last_key = sym;
 	    break;
     }
 }
@@ -4288,6 +4309,217 @@ static void SnowDemo(void)
 }
 
 #undef SNOW_LINES
+#undef SNOW_FLAKES
+
+
+/* ---------------------------------------- ROAD DEMO
+ */
+
+#define ROAD_NUM	5000
+#define ROAD_WIDTH	100
+#define ROAD_Z_INC	10
+
+static void RoadDemo(void)
+{
+    static int init = FALSE;
+
+    typedef struct
+    {
+    	double dx, dy;
+    } Road;
+
+    static Road road[ROAD_NUM];
+    static double dx, dy;
+    static double dxi, dyi;
+    static int dcount;
+
+    int f,r;
+    double x, y, z;
+    double rx, ry, rz;
+    double rx2, ry2, rz2;
+    int max_y;
+    double ang_y;
+    double ang_x;
+
+    if (!init)
+    {
+	init=TRUE;
+
+	for(f = 0; f < ROAD_NUM; f++)
+	{
+	    if (dcount == 0 && dx == 0 && dy == 0)
+	    {
+	    	dcount = RND2(20, 500);
+		dx = 0;
+		dy = 0;
+		dxi = RND(10) / 40.0 - 0.125;
+		dyi = RND(10) / 80.0 - 0.065;
+	    }
+	    else
+	    {
+		if (dcount)
+		{
+		    dcount--;
+
+		    if (dx < ROAD_Z_INC / 2.0  && dx > -ROAD_Z_INC / 2.0)
+		    {
+			dx += dxi;
+		    }
+
+		    if (dy < ROAD_Z_INC / 2.0 && dy > -ROAD_Z_INC / 2.0)
+		    {
+			dy += dyi;
+		    }
+		}
+		else
+		{
+		    double sdx = SgnF(dx);
+		    double sdy = SgnF(dy);
+
+		    dx -= dxi;
+		    dy -= dyi;
+
+		    if (SgnF(dx) != sdx)
+		    {
+		    	dx = 0;
+			dy = 0;
+		    }
+		    else if (SgnF(dy) != sdy)
+		    {
+		    	dx = 0;
+		    	dy = 0;
+		    }
+		}
+	    }
+
+	    road[f].dx = dx;
+	    road[f].dy = dy;
+	}
+    }
+
+    Cls();
+
+    x = -ROAD_WIDTH / 2;
+    y = 20.0;
+    z = 10.0;
+    max_y = height;
+
+    ang_x = atan(fabs(road[0].dy) / ROAD_Z_INC);
+
+    if (isnan(ang_x))
+    {
+    	ang_x = 0;
+    }
+    else
+    {
+    	ang_x = DEG(ang_x) * 10.0;
+
+	if (road[0].dy > 0)
+	{
+	    ang_x = -ang_x;
+	}
+    }
+
+    ang_y = atan(fabs(road[0].dx) / ROAD_Z_INC);
+
+    if (isnan(ang_y))
+    {
+    	ang_y = 0;
+    }
+    else
+    {
+    	ang_y = DEG(ang_y) * 10.0;
+
+	if (road[0].dx > 0)
+	{
+	    ang_y = -ang_y;
+	}
+    }
+
+    for(f = 0; f < ROAD_NUM; f++)
+    {
+    	XPoint xp;
+
+	x += road[f].dx;
+	y += road[f].dy;
+	z += ROAD_Z_INC;
+
+	RotateY(0, 0, 0, x, y, z, &rx, &ry, &rz, (int)ang_y);
+	RotateX(0, 0, 0, rx, ry, rz, &rx2, &ry2, &rz2, (int)ang_x);
+
+	if (Project(rx2, ry2, rz2, &xp))
+	{
+	    if (xp.y < max_y)
+	    {
+		Plot(xp.x, xp.y, white);
+
+		Project(rx2 + ROAD_WIDTH, ry2, rz2, &xp);
+		Plot(xp.x, xp.y, white);
+
+		max_y = xp.y;
+	    }
+	}
+
+	if (f < ROAD_NUM - 1)
+	{
+	    road[f] = road[f + 1];
+	}
+	else
+	{
+	    if (dcount == 0 && dx == 0 && dy == 0)
+	    {
+	    	dcount = RND2(20, 500);
+		dx = 0;
+		dy = 0;
+		dxi = RND(10) / 40.0 - 0.125;
+		dyi = RND(10) / 80.0 - 0.065;
+	    }
+	    else
+	    {
+		if (dcount)
+		{
+		    dcount--;
+
+		    if (dx < ROAD_Z_INC / 2.0  && dx > -ROAD_Z_INC / 2.0)
+		    {
+			dx += dxi;
+		    }
+
+		    if (dy < ROAD_Z_INC / 2.0 && dy > -ROAD_Z_INC / 2.0)
+		    {
+			dy += dyi;
+		    }
+		}
+		else
+		{
+		    double sdx = SgnF(dx);
+		    double sdy = SgnF(dy);
+
+		    dx -= dxi;
+		    dy -= dyi;
+
+		    if (SgnF(dx) != sdx)
+		    {
+		    	dx = 0;
+			dy = 0;
+		    }
+		    else if (SgnF(dy) != sdy)
+		    {
+		    	dx = 0;
+		    	dy = 0;
+		    }
+		}
+	    }
+
+	    road[f].dx = dx;
+	    road[f].dy = dy;
+	}
+    }
+}
+
+#undef ROAD_NUM
+#undef ROAD_WIDTH
+#undef ROAD_Z_INC
 
 
 /* END OF FILE */
-- 
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