Add shrinking gaps

Author: cxong

game.h

@@ -71,7 +71,10 @@
 
 // The width of the area to leave empty for the player to pass through.
 // Given in meters.
-#define GAP_WIDTH        0.75f
+// Gaps start out big and gradually shrink over time.
+#define GAP_WIDTH_MIN    0.75f
+#define GAP_WIDTH_MAX    1.5f
+#define GAP_WIDTH_SHRINK_SPEED -0.01f
 
 // The height of gap surfaces.
 // Given in meters.

gap.c

@@ -41,21 +41,19 @@ POSSIBILITY OF SUCH DAMAGE.
 SDL_Surface *GapSurfaces[6];
 
 static int compareFloat(const void *a, const void *b);
-void GapInit(struct Gap* gap, float y)
+void GapInit(struct Gap* gap, const float w, const float y)
 {
 	// Randomly generate some gaps, and place blocks around them
 	float gapXs[MAX_GAPS];
 	for (int i = 0; i < MAX_GAPS; i++)
 	{
-		gapXs[i] =
-			GAP_WIDTH / 2 +
-			(float)rand() / (float)RAND_MAX * (FIELD_WIDTH - GAP_WIDTH);
+		gapXs[i] = w / 2 + (float)rand() / (float)RAND_MAX * (FIELD_WIDTH - w);
 	}
 	qsort(gapXs, MAX_GAPS, sizeof gapXs[0], compareFloat);
 	// Merge gaps if they are too close
 	for (int i = 1; i < MAX_GAPS; i++)
 	{
-		if (gapXs[i] - gapXs[i - 1] < GAP_WIDTH + MIN_BLOCK_WIDTH)
+		if (gapXs[i] - gapXs[i - 1] < w + MIN_BLOCK_WIDTH)
 		{
 			gapXs[i] = (gapXs[i] + gapXs[i - 1]) / 2;
 			gapXs[i - 1] = 0;
@@ -68,9 +66,9 @@ void GapInit(struct Gap* gap, float y)
 	for (int i = 0; i < MAX_GAPS; i++)
 	{
 		if (gapXs[i] == 0) continue;
-		BlockInit(&b, left, y, gapXs[i] - GAP_WIDTH / 2 - left);
+		BlockInit(&b, left, y, gapXs[i] - w / 2 - left);
 		CArrayPushBack(&gap->blocks, &b);
-		left = gapXs[i] + GAP_WIDTH / 2;
+		left = gapXs[i] + w / 2;
 	}
 	// Add last block
 	BlockInit(&b, left, y, FIELD_WIDTH - left);

gap.h

@@ -48,7 +48,7 @@ struct Gap
 
 extern SDL_Surface *GapSurfaces[6];
 
-void GapInit(struct Gap* gap, float y);
+void GapInit(struct Gap* gap, const float w, const float y);
 void GapRemove(struct Gap* gap);
 void GapDraw(const struct Gap* gap, const float y);
 

space.c

@@ -69,6 +69,7 @@ void SpaceReset(Space *s)
 	}
 	CArrayClear(&s->Gaps);
 	s->gapGenDistance = GAP_GEN_START;
+	s->gapWidth = GAP_WIDTH_MAX;
 
 	PickupsReset();
 }
@@ -130,18 +131,19 @@ void SpaceUpdate(
 		lastGap = CArrayGet(&s->Gaps, s->Gaps.size - 1);
 	}
 	if (s->Gaps.size == 0 ||
-		GapBottom(lastGap) - (cameraY - FIELD_HEIGHT) >= s->gapGenDistance)
+		GapBottom(lastGap) - (cameraY - FIELD_HEIGHT * 2) >= s->gapGenDistance)
 	{
 		float top = 0;
 		if (s->Gaps.size != 0)
 		{
 			top = GapBottom(lastGap) - s->gapGenDistance;
-			s->gapGenDistance += GAP_GEN_SPEED;
-			s->gapGenDistance = MAX(GAP_GEN_MIN, s->gapGenDistance);
+			s->gapGenDistance =
+				MAX(GAP_GEN_MIN, s->gapGenDistance + GAP_GEN_SPEED);
 		}
 		struct Gap g;
-		GapInit(&g, top);
+		GapInit(&g, s->gapWidth, top);
 		CArrayPushBack(&s->Gaps, &g);
+		s->gapWidth = MAX(GAP_WIDTH_MIN, s->gapWidth + GAP_WIDTH_SHRINK_SPEED);
 	}
 
 	if (y < s->edgeBodiesBottom)

space.h

@@ -40,6 +40,7 @@ typedef struct
 
 	CArray Gaps;	// of Gap
 	float gapGenDistance;
+	float gapWidth;
 } Space;
 
 extern Space space;