stage: add stage_[sg]et_alpha()

Convenient for whole-stage fades...

2 files changed, 22 insertions, 5 deletions

diff --git a/src/stage.c b/src/stage.c
index b50bc22..7344104 100644
--- a/src/stage.c
+++ b/src/stage.c
@@ -52,6 +52,7 @@ struct stage_t {
 	list_head_t	layers[STAGE_LAYERS_MAX];
 	SDL_Renderer	*renderer;		/* target renderer */
 	float		aspect_ratio;		/* width/height ratio of stage, -1.0...1.0 range of node coordinates map to this ratio. */
+	float		alpha;			/* alpha to apply to all nodes */
 };
 
 
@@ -326,6 +327,20 @@ void stage_fit(const stage_t *stage, int width, int height, int *res_width, int
 }
 
 
+/* set the global alpha factor for the stage, the individual node alphas are multiplied by this value @ render time. */
+void stage_set_alpha(stage_t *stage, float alpha)
+{
+	stage->alpha = alpha;
+}
+
+
+/* get the global alpha factor for the stage */
+void stage_get_alpha(stage_t *stage, float *res_alpha)
+{
+	*res_alpha = stage->alpha;
+}
+
+
 static void aabb_to_rect(const aabb_t *aabb, const v2f_t *pos, const SDL_Rect *stage_rect, SDL_Rect *res_rect)
 {
 	float	half_w = ((float)stage_rect->w) * .5f, half_h = ((float)stage_rect->h) * .5f;	/* FIXME silly to recompute this repeatedly... */
@@ -340,7 +355,7 @@ static void aabb_to_rect(const aabb_t *aabb, const v2f_t *pos, const SDL_Rect *s
 }
 
 
-static void render_nodes(list_head_t *head, SDL_Renderer *renderer, SDL_Rect *dest_rect)
+static void render_nodes(const stage_t *stage, const list_head_t *head, SDL_Renderer *renderer, SDL_Rect *dest_rect)
 {
 	stage_node_t	*node;
 
@@ -372,7 +387,7 @@ static void render_nodes(list_head_t *head, SDL_Renderer *renderer, SDL_Rect *de
 		node->render(renderer, node->object, node_rect.w, node_rect.h, &node->cached.texture);
 		node->cached.width = node_rect.w;
 		node->cached.height = node_rect.h;
-		SDL_SetTextureAlphaMod(node->cached.texture, ((float)node->alpha * 255.0f));
+		SDL_SetTextureAlphaMod(node->cached.texture, stage->alpha * node->alpha * 255.0f);
 
 		/* copy the texture to renderer */
 		if (node->angle == 0)
@@ -399,7 +414,7 @@ void stage_get_output_size(stage_t *stage, int *res_width, int *res_height)
  * will center the rendering and leave blank borders on the edges left empty.
  * The renderer may be sized precisely by first calling stage_fit().
  */
-void stage_render(stage_t *stage)
+void stage_render(const stage_t *stage)
 {
 	SDL_Rect	rect;
 	int		i, width, height;
@@ -414,7 +429,7 @@ void stage_render(stage_t *stage)
 	SDL_RenderClear(stage->renderer);	/* TODO: handle -1 on error */
 
 	for (i = 0; i < STAGE_LAYERS_MAX; i++)
-		render_nodes(&stage->layers[i], stage->renderer, &rect);
+		render_nodes(stage, &stage->layers[i], stage->renderer, &rect);
 }
 
 
diff --git a/src/stage.h b/src/stage.h
index ff43847..6d73753 100644
--- a/src/stage.h
+++ b/src/stage.h
@@ -33,7 +33,9 @@ stage_t * stage_new(SDL_Renderer *renderer, float aspect_ratio);
 void stage_clear(stage_t *stage);
 stage_t * stage_free(stage_t *stage);
 void stage_fit(const stage_t *stage, int width, int height, int *res_width, int *res_height);
-void stage_render(stage_t *stage);
+void stage_set_alpha(stage_t *stage, float alpha);
+void stage_get_alpha(stage_t *stage, float *res_alpha);
+void stage_render(const stage_t *stage);
 stage_node_t * stage_node_new(stage_t *stage, int layer, const char *name, void *object, stage_render_func_t render_func, stage_free_func_t free_func);
 
 void stage_get_output_size(stage_t *stage, int *res_width, int *res_height);