Implementing ABS/REL draw with beam ON/OFF/

imlac_sdl/animation/test.c

@@ -8,69 +8,68 @@
 
 #define SAVEFILE  "snapshot.png"
 
+enum BEAM {OFF, ON};	// beam ON/OFF
+enum OP {ABS, REL};	// absolute/relative moves
+
 typedef struct
 {
-    int x1;
-    int y1;
-    int x2;
-    int y2;
-    int dy1;
-    int dy2;
-    bool end;
+    enum OP type;
+    enum BEAM beam;
+    int dx;
+    int dy;
 } DLine;
 
-DLine drawlist[]  = {{0, 0, WIDTH, HEIGHT, 1, 1, false},
-	             {0, HEIGHT, WIDTH, 0, 1, 1, false},
-		     {0, HEIGHT/2, HEIGHT, HEIGHT/2, -1, -1, true}
-	            };
+#define DRAWLIST_SIZE	1000
 
-int len_drawlist = 3;
+DLine drawlist[DRAWLIST_SIZE];
+
+// index of drawlist entry AFTER last instruction
+unsigned int drawlist_end = 0;
+
+//-------------------------
+// Define some characters with relative moves
+//-------------------------
+
+DLine Char_I[] = {{REL, OFF, 0, -6},
+	          {REL, ON, 2, 0},
+		  {REL, OFF, -1, 0},
+		  {REL, ON, 0, 6},
+		  {REL, OFF, -1, 0},
+		  {REL, ON, 2, 0},
+	         };
+
+DLine Char_m[] = {{REL, ON, 0, -3},
+	          {REL, ON, 1, -1},
+	          {REL, ON, 0, 1},
+	          {REL, OFF, 0, -1},
+	          {REL, ON, 1, -1},
+	          {REL, ON, 1, 1},
+	          {REL, ON, 0, 3},
+		 };
+
+int Magnification = 5;
 
 
-DLine *
+unsigned int
 make_drawlist(void)
 {
-    for (int dindex = 0; dindex < len_drawlist; ++dindex)
-    {
-	int x1 = drawlist[dindex].x1;
-	int y1 = drawlist[dindex].y1;
-	int x2 = drawlist[dindex].x2;
-	int y2 = drawlist[dindex].y2;
-	int dy1 = drawlist[dindex].dy1;
-	int dy2 = drawlist[dindex].dy2;
+    drawlist_end = 0;
 
-        y1 += dy1;
-        if (y1 >= HEIGHT)
-        {
-            y1 = HEIGHT;
-	    dy1 = -1;
-        }
-	if (y1 <= 0)
-	{
-	    y1 = 0;
-	    dy1 = +1;
-	}
+    DLine dline = {ABS, OFF, 100, 100};
+    memcpy(&drawlist[drawlist_end], &dline, sizeof(DLine));
+    ++drawlist_end;
 
-	drawlist[dindex].y1 = y1;
-	drawlist[dindex].dy1 = dy1;
+    memcpy(&drawlist[drawlist_end], Char_I, sizeof(Char_I));
+    drawlist_end += sizeof(Char_I); 
 
-        y2 += dy2;
-        if (y2 >= HEIGHT)
-        {
-            y2 = HEIGHT;
-	    dy2 = -1;
-        }
-	if (y2 <= 0)
-	{
-	    y2 = 0;
-	    dy2 = +1;
-	}
- 
-	drawlist[dindex].y2 = y2;
-	drawlist[dindex].dy2 = dy2;
-    }
+    DLine dline2 = {ABS, OFF, 106, 100};
+    memcpy(&drawlist[drawlist_end], &dline2, sizeof(DLine));
+    ++drawlist_end;
 
-    return drawlist;
+    memcpy(&drawlist[drawlist_end], Char_m, sizeof(Char_m));
+    drawlist_end += sizeof(Char_m); 
+
+    return drawlist_end;
 }
 
 
@@ -116,7 +115,6 @@ saveScreenshotBMP(char *savefile, SDL_Window* window, SDL_Renderer* renderer)
                     return false;
                 }
                 IMG_SavePNG(save_surface, SAVEFILE);
-//                SDL_SavePNG(save_surface, savefile);
                 SDL_FreeSurface(save_surface);
                 save_surface = NULL;
             }
@@ -152,7 +150,7 @@ main(int argc, char **argv)
     // handle events
     while (!quit)
     {
-        DLine *drawlist = make_drawlist();
+        drawlist_end = make_drawlist();
 
         SDL_Delay(5);
         SDL_PollEvent(&event);
@@ -179,21 +177,42 @@ main(int argc, char **argv)
         SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
         SDL_RenderClear(renderer);
  
-        // render the draw list, set draw colour
+        // set draw colour
         SDL_SetRenderDrawColor(renderer, 200, 255, 200, 255);
 
+	// set beam at (0, 0)
+	unsigned int abs_x = 0;
+	unsigned int abs_y = 0;
+
 	// draw the drawlist
-        for (int dindex = 0; dindex < len_drawlist; ++dindex)
+        for (int dindex = 0; dindex < drawlist_end; ++dindex)
 	{
-	    int x1 = drawlist[dindex].x1;
-	    int y1 = drawlist[dindex].y1;
-	    int x2 = drawlist[dindex].x2;
-	    int y2 = drawlist[dindex].y2;
+            enum OP type = drawlist[dindex].type;
+            enum BEAM beam = drawlist[dindex].beam;
+            int dx = drawlist[dindex].dx * Magnification;
+            int dy = drawlist[dindex].dy * Magnification;
+	    unsigned int new_x;
+	    unsigned int new_y;
 
-            SDL_RenderDrawLine(renderer, x1, y1, x2, y2);
+	    if (type == ABS)
+	    {
+		new_x = dx;
+		new_y = dy;
 
-	    if (drawlist[dindex].end)
-		break;
+		if (beam == ON)
+                    SDL_RenderDrawLine(renderer, abs_x, abs_y, new_x + 1, new_y + 1);
+	    }
+	    else
+	    {
+	        new_x = abs_x + dx;
+	        new_y = abs_y + dy;
+
+		if (beam == ON)
+                    SDL_RenderDrawLine(renderer, abs_x, abs_y, new_x + 1, new_y + 1);
+	    }
+
+	    abs_x = new_x;
+	    abs_y = new_y;
 	}
 
         // render window