[gtk/gamma-shenanigans: 3/9] Support 16-bit floating point textures

[Matthias Clasen <matthiasc src gnome org>]

commit 1708a1dc3606333122eae3001d643a83c3bf9dd3
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Sep 6 08:27:42 2021 -0400

    Support 16-bit floating point textures
    
    Add R16G16B16_FLOAT and R16B16B16A16_FLOAT_PREMULTIPLIED
    formats, which are using half floats.
    
    The intention is to use these for HDR content.
    
    Not done here: Update memory texture tests
    to include floating point textures.

 gdk/gdkglcontext.c            | 14 ++++++++
 gdk/gdkgltexture.c            |  7 ++++
 gdk/gdkmemorytexture.c        | 75 ++++++++++++++++++++++++++++++++++++++++++-
 gdk/gdkmemorytexture.h        |  7 ++++
 testsuite/gdk/memorytexture.c |  4 +++
 5 files changed, 106 insertions(+), 1 deletion(-)
---
diff --git a/gdk/gdkglcontext.c b/gdk/gdkglcontext.c
index 0754f40703..7c535f2ce8 100644
--- a/gdk/gdkglcontext.c
+++ b/gdk/gdkglcontext.c
@@ -292,6 +292,20 @@ gdk_gl_context_upload_texture (GdkGLContext    *context,
           gl_type = GL_UNSIGNED_SHORT;
           bpp = 8;
         }
+      else if (data_format == GDK_MEMORY_R16G16B16_FLOAT)
+        {
+          gl_internalformat = GL_RGB16F;
+          gl_format = GL_RGB;
+          gl_type = GL_HALF_FLOAT;
+          bpp = 6;
+        }
+      else if (data_format == GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED)
+        {
+          gl_internalformat = GL_RGBA16F;
+          gl_format = GL_RGBA;
+          gl_type = GL_HALF_FLOAT;
+          bpp = 8;
+        }
       else /* Fall-back, convert to cairo-surface-format */
         {
           copy = g_malloc (width * height * 4);
diff --git a/gdk/gdkgltexture.c b/gdk/gdkgltexture.c
index f0d3e40ac6..45226fa50c 100644
--- a/gdk/gdkgltexture.c
+++ b/gdk/gdkgltexture.c
@@ -120,6 +120,9 @@ type_from_internal_format (int internal_format)
     case GL_RGB16:
     case GL_RGBA16:
       return GL_UNSIGNED_SHORT;
+    case GL_RGB16F:
+    case GL_RGBA16F:
+      return GL_HALF_FLOAT;
     default:
       g_assert_not_reached ();
     }
@@ -134,6 +137,10 @@ internal_format_for_format (GdkMemoryFormat format)
       return GL_RGB16;
     case GDK_MEMORY_R16G16B16A16_PREMULTIPLIED:
       return GL_RGBA16;
+    case GDK_MEMORY_R16G16B16_FLOAT:
+      return GL_RGB16F;
+    case GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED:
+      return GL_RGB16F;
     default:
       g_assert_not_reached ();
     }
diff --git a/gdk/gdkmemorytexture.c b/gdk/gdkmemorytexture.c
index d6460ffc71..101d715232 100644
--- a/gdk/gdkmemorytexture.c
+++ b/gdk/gdkmemorytexture.c
@@ -20,6 +20,7 @@
 #include "config.h"
 
 #include "gdkmemorytextureprivate.h"
+#include "gsk/ngl/fp16private.h"
 
 /**
  * GdkMemoryTexture:
@@ -66,8 +67,12 @@ gdk_memory_format_bytes_per_pixel (GdkMemoryFormat format)
       return 6;
 
     case GDK_MEMORY_R16G16B16A16_PREMULTIPLIED:
+    case GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED:
       return 8;
 
+    case GDK_MEMORY_R16G16B16_FLOAT:
+      return 6;
+
     case GDK_MEMORY_N_FORMATS:
     default:
       g_assert_not_reached ();
@@ -364,6 +369,72 @@ SWIZZLE_16TO8(0,1,2,3)
 SWIZZLE_16TO8(2,1,0,3)
 SWIZZLE_16TO8(1,2,3,0)
 
+#define SWIZZLE_FP16_OPAQUE(A,R,G,B) \
+static void \
+convert_fp16_swizzle_opaque_ ## A ## R ## G ## B (guchar       *dest_data, \
+                                                  gsize         dest_stride, \
+                                                  const guchar *src_data, \
+                                                  gsize         src_stride, \
+                                                  gsize         width, \
+                                                  gsize         height) \
+{ \
+  gsize x, y; \
+\
+  for (y = 0; y < height; y++) \
+    { \
+      guint16 *src = (guint16 *)src_data; \
+      for (x = 0; x < width; x++) \
+        { \
+          float c[4]; \
+          half_to_float4 (&src[3 * x], c); \
+          dest_data[4 * x + A] = 255; \
+          dest_data[4 * x + R] = (guchar)(255 * c[0]); \
+          dest_data[4 * x + G] = (guchar)(255 * c[1]); \
+          dest_data[4 * x + B] = (guchar)(255 * c[2]); \
+        } \
+\
+      dest_data += dest_stride; \
+      src_data += src_stride; \
+    } \
+}
+
+SWIZZLE_FP16_OPAQUE(3,2,1,0)
+SWIZZLE_FP16_OPAQUE(0,1,2,3)
+SWIZZLE_FP16_OPAQUE(3,0,1,2)
+
+#define SWIZZLE_FP16(A,R,G,B) \
+static void \
+convert_fp16_swizzle_ ## A ## R ## G ## B (guchar       *dest_data, \
+                                           gsize         dest_stride, \
+                                           const guchar *src_data, \
+                                           gsize         src_stride, \
+                                           gsize         width, \
+                                           gsize         height) \
+{ \
+  gsize x, y; \
+\
+  for (y = 0; y < height; y++) \
+    { \
+      guint16 *src = (guint16 *)src_data; \
+      for (x = 0; x < width; x++) \
+        { \
+          float c[4]; \
+          half_to_float4 (&src[3 * x], c); \
+          dest_data[4 * x + A] = (guchar)(255 * c[0]); \
+          dest_data[4 * x + R] = (guchar)(255 * c[1]); \
+          dest_data[4 * x + G] = (guchar)(255 * c[2]); \
+          dest_data[4 * x + B] = (guchar)(255 * c[3]); \
+        } \
+\
+      dest_data += dest_stride; \
+      src_data += src_stride; \
+    } \
+}
+
+SWIZZLE_FP16(3,2,1,0)
+SWIZZLE_FP16(0,1,2,3)
+SWIZZLE_FP16(3,0,1,2)
+
 typedef void (* ConversionFunc) (guchar       *dest_data,
                                  gsize         dest_stride,
                                  const guchar *src_data,
@@ -383,7 +454,9 @@ static ConversionFunc converters[GDK_MEMORY_N_FORMATS][3] =
   { convert_swizzle_opaque_3210, convert_swizzle_opaque_0123, convert_swizzle_opaque_3012 },
   { convert_swizzle_opaque_3012, convert_swizzle_opaque_0321, convert_swizzle_opaque_3210 },
   { convert_16to8_swizzle_opaque_2103, convert_16to8_swizzle_opaque_1230, convert_16to8_swizzle_opaque_0123 
},
-  { convert_16to8_swizzle_2103, convert_16to8_swizzle_1230, convert_16to8_swizzle_0123 }
+  { convert_16to8_swizzle_2103, convert_16to8_swizzle_1230, convert_16to8_swizzle_0123 },
+  { convert_fp16_swizzle_opaque_3210, convert_fp16_swizzle_opaque_0123, convert_fp16_swizzle_opaque_3012 },
+  { convert_fp16_swizzle_3210, convert_fp16_swizzle_0123, convert_fp16_swizzle_3012 }
 };
 
 void
diff --git a/gdk/gdkmemorytexture.h b/gdk/gdkmemorytexture.h
index cac6fa52f7..5bab062d6f 100644
--- a/gdk/gdkmemorytexture.h
+++ b/gdk/gdkmemorytexture.h
@@ -46,6 +46,11 @@ G_BEGIN_DECLS
  * @GDK_MEMORY_R16G16B16A16_PREMULTIPLIED: 4 guint16 values; for red, green,
  *   blue, alpha. The color values are premultiplied with the alpha value.
  *   Since 4.6
+ * @GDK_MEMORY_R16G16B16_FLOAT: 3 half-float values; for red, green, blue.
+ *   The data is opaque. Since 4.6
+ * @GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED: 4 half-float values; for
+ *   red, green, blue and alpha. The color values are premultiplied with
+ *   the alpha value. Since 4.6
  * @GDK_MEMORY_N_FORMATS: The number of formats. This value will change as
  *   more formats get added, so do not rely on its concrete integer.
  *
@@ -75,6 +80,8 @@ typedef enum {
   GDK_MEMORY_B8G8R8,
   GDK_MEMORY_R16G16B16,
   GDK_MEMORY_R16G16B16A16_PREMULTIPLIED,
+  GDK_MEMORY_R16G16B16_FLOAT,
+  GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED,
 
   GDK_MEMORY_N_FORMATS
 } GdkMemoryFormat;
diff --git a/testsuite/gdk/memorytexture.c b/testsuite/gdk/memorytexture.c
index 00bb489b63..8645a96fec 100644
--- a/testsuite/gdk/memorytexture.c
+++ b/testsuite/gdk/memorytexture.c
@@ -189,6 +189,10 @@ main (int argc, char *argv[])
 
   for (format = 0; format < GDK_MEMORY_N_FORMATS; format++)
     {
+      if (format == GDK_MEMORY_R16G16B16_FLOAT ||
+          format == GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED)
+        continue;
+
       for (color = 0; color < N_COLORS; color++)
         {
           TestData *test_data = g_new (TestData, 1);