add bg-style.[hc]

3 files changed, 94 insertions, 27 deletions

diff --git a/src/sdl/bg-style.c b/src/sdl/bg-style.c
new file mode 100644
index 0000000..02bc759
--- /dev/null
+++ b/src/sdl/bg-style.c
@@ -0,0 +1,21 @@
+#include <math.h> // sin()
+#include "bg-style.h"
+
+#define M_2_PI (2.0 * 3.1415926)
+
+#define BG_STYLE_GET_CHANNEL(c, time) ((c).base + (((c).period) ? ( \
+  (c).amplitude * sin(((c).phase + (time)) * M_2_PI / (1.0 * (c).period)) \
+) : 0))
+
+SDL_Color
+bg_style_get_color(
+  const bg_style_t * const style,
+  const Uint32 ticks
+) {
+  return (SDL_Color) {
+    .r = BG_STYLE_GET_CHANNEL(style->r, ticks),
+    .g = BG_STYLE_GET_CHANNEL(style->g, ticks),
+    .b = BG_STYLE_GET_CHANNEL(style->b, ticks),
+    .a = BG_STYLE_GET_CHANNEL(style->a, ticks),
+  };
+}
diff --git a/src/sdl/bg-style.h b/src/sdl/bg-style.h
new file mode 100644
index 0000000..c4ca9a5
--- /dev/null
+++ b/src/sdl/bg-style.h
@@ -0,0 +1,21 @@
+#ifndef BG_STYLE_H
+#define BG_STYLE_H
+
+#include <SDL.h> // SDL_Color
+
+typedef struct {
+  struct {
+    int base,
+        amplitude,
+        phase,
+        period;
+  } r, g, b, a;
+} bg_style_t;
+
+SDL_Color
+bg_style_get_color(
+  const bg_style_t * const,
+  const Uint32
+);
+
+#endif /* BG_STYLE_H */
diff --git a/src/sdl/draw.c b/src/sdl/draw.c
index 418ddd2..482bfb2 100644
--- a/src/sdl/draw.c
+++ b/src/sdl/draw.c
@@ -5,6 +5,7 @@
 #include "draw.h"
 #include "sprites.h"
 #include "draw-text.h"
+#include "bg-style.h"
 
 #define M_2_PI (2.0 * 3.1415926)
 
@@ -255,7 +256,6 @@ HELP_STYLE = {
   },
 };
 
-#define DELIM "     "
 
 static void
 draw_help_text(
@@ -263,55 +263,80 @@ draw_help_text(
 ) {
   // build text
   char buf[256];
+#define D "     "
   snprintf(
     buf, sizeof(buf),
-    " %sU: Undo" DELIM "R: Reset" DELIM "S: Solve" DELIM "Q: Quit ",
-    sok_ctx_is_done(draw_ctx->ctx) ? "Space: Next Level" DELIM : ""
+    " %sU: Undo" D "R: Reset" D "S: Solve" D "Q: Quit ",
+    sok_ctx_is_done(draw_ctx->ctx) ? "Space: Next Level" D : ""
   );
+#undef D
 
   // draw text
   draw_text(draw_ctx->renderer, draw_ctx->font, &HELP_STYLE, buf);
 }
 
+static const bg_style_t
+BG_STYLES[] = {{
+  // normal style
+  .r = { .base = 0x00 },
+  .g = { .base = 0x00 },
+  .b = { .base = 0x00 },
+  .a = { .base = 0xFF },
+}, {
+  // won style
+  .r = {
+    .base       = 0x66,
+    .amplitude  = 0x33,
+    .phase      = 1000,
+    .period     = 2000,
+  },
+
+  .g = {
+    .base       = 0x66,
+    .amplitude  = 0x33,
+    .phase      = 3000,
+    .period     = 5000,
+  },
+
+  .b = {
+    .base       = 0x66,
+    .amplitude  = 0x33,
+    .phase      = 5000,
+    .period     = 7000,
+  },
+
+  .a = {
+    .base       = 0xFF,
+  },
+}};
+
 static void
-set_bg_won_color(
+draw_bg(
   draw_ctx_t * const draw_ctx
 ) {
-  const Uint32 ticks = SDL_GetTicks();
-
-  // gen color
-  const SDL_Color c = {
-    .r = 0x66 + 0x33 * sinf((1000 + ticks) * M_2_PI / 2000.0),
-    .g = 0x66 + 0x33 * sinf((3000 + ticks) * M_2_PI / 5000.0),
-    .b = 0x66 + 0x33 * sinf((5000 + ticks) * M_2_PI / 7000.0),
-    .a = 0xFF,
-  };
+  // get color
+  const SDL_Color c = bg_style_get_color(
+    BG_STYLES + (sok_ctx_is_done(draw_ctx->ctx) ? 1 : 0),
+    SDL_GetTicks()
+  );
 
   // set color
   if (SDL_SetRenderDrawColor(draw_ctx->renderer, c.r, c.g, c.b, c.a)) {
     die("SDL_SetRenderDrawColor(): %s", SDL_GetError());
   }
+
+  // clear background
+  SDL_RenderClear(draw_ctx->renderer);
 }
 
 void
 draw(
   draw_ctx_t * const draw_ctx
 ) {
-  const bool is_done = sok_ctx_is_done(draw_ctx->ctx);
-
-  // set bg color
-  if (sok_ctx_is_done(draw_ctx->ctx)) {
-    // set bg won color
-    set_bg_won_color(draw_ctx);
-  } else {
-    // set normal bg color
-    set_color(draw_ctx->renderer, is_done ? COLOR_BG_WON : COLOR_BG);
-  }
-
   // clear background
-  SDL_RenderClear(draw_ctx->renderer);
+  draw_bg(draw_ctx);
 
-  // render
+  // render level
   sok_ctx_walk(draw_ctx->ctx, &DRAW_CBS, draw_ctx);
 
   // render text
@@ -319,6 +344,6 @@ draw(
   draw_moves_text(draw_ctx);
   draw_help_text(draw_ctx);
 
-    // flip
+  // flip
   SDL_RenderPresent(draw_ctx->renderer);
 }