more mandelbrot

Makefile

@@ -1,11 +1,16 @@
 CFLAGS=-std=c99 -Wall -g
 INDENTOPTS=-kr --no-tabs --braces-on-func-def-line --indent-level2
 
-all: approximate-pi linked-list
+.PHONY: all
+all: approximate-pi linked-list mandelbrot
 
+.PHONY: clean
 clean:
-	rm -f approximate-pi linked-list *~
+	rm -f approximate-pi linked-list mandelbrot *~
 
 .PHONY: indent
 indent:
 	indent $(INDENTOPTS) *.c
+
+mandelbrot: mandelbrot.c
+	$(CC) $(CFLAGS) $(shell sdl-config --cflags) -o $@ $< $(shell sdl-config --libs) -lm

mandelbrot.c

@@ -22,8 +22,8 @@ int main(int argc, char *argv[]) {
       printf("y = %d\n", y);
     }
 
-    float complex c =     (3.0 * x / 640.0) - 2.0
-                    + I * ((2.0 * y / 480.0) - 1.0);
+    float complex c =     ((3.0 * x / screen->w) - 2.0)
+                    + I * ((2.0 * y / screen->h) - 1.0);
 
     bool diverges = false;
     float complex z = 0;
@@ -36,17 +36,21 @@ int main(int argc, char *argv[]) {
       }
     }
 
-    Uint32 color = 0x00000000;
+    Uint32 color;
     if (diverges) {
-      color = 0x01010101 * it;
+      color = 0x00020304 * it;
+    } else {
+      color = 0x00000000;
     }
 
     pixels[i] = color;
+    if (y % 10 == 0)
+      SDL_Flip(screen);
   }
   if (SDL_MUSTLOCK(screen)) {
     SDL_UnlockSurface(screen);
   }
-  SDL_Flip(screen);            /* XXX */
+  SDL_Flip(screen);
 
   SDL_Delay(20000);