Global gamma correction

2 files changed, 80 insertions, 45 deletions

diff --git a/graphics.c b/graphics.c
index f4bc699..3552792 100644
--- a/graphics.c
+++ b/graphics.c
@@ -50,13 +50,7 @@ vec4_f32 vec4_f32_lerp     (vec4_f32 a, vec4_f32 b, f32 t);
 
 //  ================================================================
 
-typedef struct {
-  //  NOTE: Dimensions are in pixels.
-  i64       width;
-  i64       height;
-  i64       stride;
-  vec4_f32 *pixels;
-} Pixel_Buffer;
+//  NOTE: Dimensions are in pixels.
 
 typedef struct {
   f64 x;
@@ -65,6 +59,31 @@ typedef struct {
   f64 height;
 } Box;
 
+//  TODO:
+// typedef struct {
+//   b8  enabled;
+//   i64 x;
+//   i64 y;
+//   i64 width;
+//   i64 height;
+// } Bounding_Box;
+
+typedef struct {
+  i64 width;
+  i64 height;
+  i64 stride;
+  // Bounding_Box bounds;
+  u8 *pixels;
+} Stencil_Buffer;
+
+typedef struct {
+  i64       width;
+  i64       height;
+  i64       stride;
+  // Bounding_Box bounds;
+  vec4_f32 *pixels;
+} Pixel_Buffer;
+
 enum {
   GRAPHICS_DRAW_PIXELS,
   GRAPHICS_FILL_RECTANGLE,
@@ -981,49 +1000,37 @@ vec4_f32 vec4_f32_lerp(vec4_f32 a, vec4_f32 b, f32 t) {
 
 //  ================================================================
 
-static f64 gamma_(f64 x) {
-  if (x >= 0.0031308)
-    return 1.055 * pow(x, 1.0 / 2.4) - 0.055;
-  return 12.92 * x;
-}
-
-static f64 gamma_re_(f64 x) {
-  if (x >= 0.04045)
-    return pow((x + 0.055) / 1.055, 2.4);
-  return x / 12.92;
-}
-
 vec3_f32 rgb_gamma_add(vec3_f32 rgb) {
   return (vec3_f32) {
-    .x = (f32) gamma_(rgb.x),
-    .y = (f32) gamma_(rgb.y),
-    .z = (f32) gamma_(rgb.z),
+    .x = gamma_(rgb.x),
+    .y = gamma_(rgb.y),
+    .z = gamma_(rgb.z),
   };
 }
 
 vec3_f32 rgb_gamma_remove(vec3_f32 rgb) {
   return (vec3_f32) {
-    .x = (f32) gamma_re_(rgb.x),
-    .y = (f32) gamma_re_(rgb.y),
-    .z = (f32) gamma_re_(rgb.z),
+    .x = gamma_re_(rgb.x),
+    .y = gamma_re_(rgb.y),
+    .z = gamma_re_(rgb.z),
   };
 }
 
 vec4_f32 rgba_gamma_add(vec4_f32 rgba) {
   return (vec4_f32) {
-    .x = (f32) gamma_(rgba.x),
-    .y = (f32) gamma_(rgba.y),
-    .z = (f32) gamma_(rgba.z),
-    .w = (f32) gamma_(rgba.w),
+    .x = gamma_(rgba.x),
+    .y = gamma_(rgba.y),
+    .z = gamma_(rgba.z),
+    .w = gamma_(rgba.w),
   };
 }
 
 vec4_f32 rgba_gamma_remove(vec4_f32 rgba) {
   return (vec4_f32) {
-    .x = (f32) gamma_re_(rgba.x),
-    .y = (f32) gamma_re_(rgba.y),
-    .z = (f32) gamma_re_(rgba.z),
-    .w = (f32) gamma_re_(rgba.w),
+    .x = gamma_re_(rgba.x),
+    .y = gamma_re_(rgba.y),
+    .z = gamma_re_(rgba.z),
+    .w = gamma_re_(rgba.w),
   };
 }
 
@@ -2186,7 +2193,7 @@ TEST("colors") {
   vec3_f32 white = rgb_from_lch(lch_from_rgb((vec3_f32) { 1.f, 1.f, 1.f, }));
   REQUIRE_EQ(white.x * 100, 100);
   REQUIRE_EQ(white.y * 100, 100);
-  REQUIRE_EQ((white.z + 3e-7) * 100, 100);
+  REQUIRE_EQ((white.z + 6e-7) * 100, 100);
 
   vec3_f32 black = rgb_from_lch(lch_from_rgb((vec3_f32) { 0.f, 0.f, 0.f, }));
   REQUIRE_EQ(black.x * 100, 0);
@@ -2205,13 +2212,13 @@ TEST("colors") {
 
   vec3_f32 green = rgb_from_lch(lch_from_rgb((vec3_f32) { 0.f, 1.f, 0.f, }));
   REQUIRE_EQ(green.x * 100,   0);
-  REQUIRE_EQ(green.y * 100, 100);
+  REQUIRE_EQ((green.y + 3e-7) * 100, 100);
   REQUIRE_EQ(green.z * 100,   0);
 
   vec3_f32 blue = rgb_from_lch(lch_from_rgb((vec3_f32) { 0.f, 0.f, 1.f, }));
   REQUIRE_EQ(blue.x * 100, 0);
   REQUIRE_EQ(blue.y * 100, 0);
-  REQUIRE_EQ((blue.z + 6e-8) * 100, 100);
+  REQUIRE_EQ((blue.z + 3e-7) * 100, 100);
 
   vec3_f32 yellow = rgb_from_lch(lch_from_rgb((vec3_f32) { 1.f, 1.f, 0.f, }));
   REQUIRE_EQ(yellow.x * 100, 100);
@@ -2220,13 +2227,13 @@ TEST("colors") {
 
   vec3_f32 cyan = rgb_from_lch(lch_from_rgb((vec3_f32) { 0.f, 1.f, 1.f, }));
   REQUIRE_EQ(cyan.x * 100,   0);
-  REQUIRE_EQ((cyan.y + 2e-7) * 100, 100);
-  REQUIRE_EQ((cyan.z + 2e-7) * 100, 100);
+  REQUIRE_EQ((cyan.y + 3e-7) * 100, 100);
+  REQUIRE_EQ((cyan.z + 3e-7) * 100, 100);
 
   vec3_f32 purple = rgb_from_lch(lch_from_rgb((vec3_f32) { 1.f, 0.f, 1.f, }));
   REQUIRE_EQ(purple.x * 100, 100);
   REQUIRE_EQ(purple.y * 100, 0);
-  REQUIRE_EQ((purple.z + 2e-7) * 100, 100);
+  REQUIRE_EQ((purple.z + 3e-7) * 100, 100);
 }
 
 TEST("rectangle corners") {
diff --git a/runtime.c b/runtime.c
index 4ba5c15..3f20820 100644
--- a/runtime.c
+++ b/runtime.c
@@ -612,7 +612,7 @@ typedef struct {
   i32 antialiasing_scale;
 
   b8 exact_resolution       : 1;
-  b8 disable_gamma          : 1; // TODO
+  b8 disable_gamma          : 1;
   b8 graceful_shutdown      : 1;
   b8 enable_clipboard_text  : 1;
   b8 enable_clipboard_image : 1;
@@ -1290,6 +1290,18 @@ i8 utf8_write(c32 c, c8 *buffer) {
 //
 //  ================================================================
 
+static f32 gamma_(f32 x) {
+  if (x >= 0.0031308f)
+    return 1.055f * (f32) pow(x, 1.0 / 2.4) - 0.055f;
+  return 12.92f * x;
+}
+
+static f32 gamma_re_(f32 x) {
+  if (x >= 0.04045f)
+    return (f32) pow((x + 0.055f) / 1.055f, 2.4);
+  return x / 12.92f;
+}
+
 static u32 rgb_u32_from_f32_(vec3_f32 c) {
   i32 ir = (i32) floor(c.x * 255. + .5);
   i32 ig = (i32) floor(c.y * 255. + .5);
@@ -1765,6 +1777,8 @@ static void convert_pixels_for_window_(void) {
     return;
   }
 
+  //  TODO, PERF: Improve performance.
+
   //  Downscale pixels from vec4_f32 pixel buffer to internal u32 pixel buffer.
   //
   //  FIXME: Check if the scale is 1:1.
@@ -1812,11 +1826,27 @@ static void convert_pixels_for_window_(void) {
         }
       }
 
-      u32      *d_end = d + dst_width;
-      vec3_f32 *im    = _internal_row;
+      u32      *d_end  = d + dst_width;
+      vec3_f32 *im     = _internal_row;
+      vec3_f32 *im_end = _internal_row + dst_width;
+
+      if (!g_platform.disable_gamma)
+        for (; im < im_end; ++im) {
+          im->x = gamma_(im->x * k);
+          im->y = gamma_(im->y * k);
+          im->z = gamma_(im->z * k);
+        }
+      else
+        for (; im < im_end; ++im) {
+          im->x *= k;
+          im->y *= k;
+          im->z *= k;
+        }
+
+      im = _internal_row;
 
       for (; d < d_end; ++d, ++im)
-        *d = rgb_u32_from_f32_((vec3_f32) { .x = im->x * k, .y = im->y * k, .z = im->z * k, }) | 0xff000000;
+        *d = rgb_u32_from_f32_(*im) | 0xff000000;
     }
 
     PROFILER_end(PROFILE_DOWNSCALE);
@@ -1843,8 +1873,6 @@ static void convert_pixels_for_window_(void) {
 
     PROFILER_begin(PROFILE_RESIZE);
 
-    //  TODO, PERF: Improve performance.
-
     u32 x_ratio = (src_width  << 16) / dst_width;
     u32 y_ratio = (src_height << 16) / dst_height;