[gtk/gamma-shenanigans: 2/4] Support 32-bit floating point textures

[Matthias Clasen <matthiasc src gnome org>]

commit 169097fbf0a991b3e73162e6e78da0316338bd5b
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Sep 7 12:44:08 2021 -0400

    Support 32-bit floating point textures
    
    Add R32G32B32_FLOAT and R32G32B32A32_FLOAT_PREMULTIPLIED
    formats which are using 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            | 13 ++++++++
 gdk/gdkmemorytexture.c        | 74 +++++++++++++++++++++++++++++++++++++++++--
 gdk/gdkmemorytexture.h        |  7 ++++
 testsuite/gdk/memorytexture.c |  3 +-
 5 files changed, 108 insertions(+), 3 deletions(-)
---
diff --git a/gdk/gdkglcontext.c b/gdk/gdkglcontext.c
index de20454858..0fdb6f2fda 100644
--- a/gdk/gdkglcontext.c
+++ b/gdk/gdkglcontext.c
@@ -299,6 +299,20 @@ gdk_gl_context_upload_texture (GdkGLContext    *context,
           gl_type = GL_HALF_FLOAT;
           bpp = 8;
         }
+      else if (data_format == GDK_MEMORY_R32G32B32_FLOAT)
+        {
+          gl_internalformat = GL_RGB32F;
+          gl_format = GL_RGB;
+          gl_type = GL_FLOAT;
+          bpp = 12;
+        }
+      else if (data_format == GDK_MEMORY_R32G32B32A32_FLOAT_PREMULTIPLIED)
+        {
+          gl_internalformat = GL_RGBA32F;
+          gl_format = GL_RGBA;
+          gl_type = GL_FLOAT;
+          bpp = 16;
+        }
       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 0a0460aefa..981414f9f0 100644
--- a/gdk/gdkgltexture.c
+++ b/gdk/gdkgltexture.c
@@ -140,6 +140,19 @@ gdk_gl_texture_download_format (GdkTexture      *texture,
       glReadPixels (0, 0, texture->width, texture->height,
                     GL_RGBA16, GL_UNSIGNED_SHORT, data);
 
+      return g_bytes_new_take (data, size);
+    }
+  else if (format == GDK_MEMORY_R32G32B32_FLOAT)
+    {
+      if (format != GL_RGB32F)
+        return NULL;
+
+      size = texture->width * texture->height * 3 * sizeof (float);
+      data = malloc (size);
+
+      glReadPixels (0, 0, texture->width, texture->height,
+                    GL_RGBA32F, GL_FLOAT, data);
+
       return g_bytes_new_take (data, size);
     }
   else
diff --git a/gdk/gdkmemorytexture.c b/gdk/gdkmemorytexture.c
index 6952b4343f..a614cf2d81 100644
--- a/gdk/gdkmemorytexture.c
+++ b/gdk/gdkmemorytexture.c
@@ -70,6 +70,12 @@ gdk_memory_format_bytes_per_pixel (GdkMemoryFormat format)
     case GDK_MEMORY_R16G16B16_FLOAT:
       return 6;
 
+    case GDK_MEMORY_R32G32B32_FLOAT:
+      return 12;
+
+    case GDK_MEMORY_R32G32B32A32_FLOAT_PREMULTIPLIED:
+      return 16;
+
     case GDK_MEMORY_N_FORMATS:
     default:
       g_assert_not_reached ();
@@ -169,7 +175,7 @@ gdk_memory_texture_new (int              width,
   return GDK_TEXTURE (self);
 }
 
-GdkMemoryFormat 
+GdkMemoryFormat
 gdk_memory_texture_get_format (GdkMemoryTexture *self)
 {
   return self->format;
@@ -401,6 +407,68 @@ SWIZZLE_FP16(3,2,1,0)
 SWIZZLE_FP16(0,1,2,3)
 SWIZZLE_FP16(3,0,1,2)
 
+#define SWIZZLE_FLOAT_OPAQUE(A,R,G,B) \
+static void \
+convert_float_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++) \
+    { \
+      float *src = (float *)src_data; \
+      for (x = 0; x < width; x++) \
+        { \
+          dest_data[4 * x + A] = 255; \
+          dest_data[4 * x + R] = (guchar)(255 * src[3 * x + 0]); \
+          dest_data[4 * x + G] = (guchar)(255 * src[3 * x + 1]); \
+          dest_data[4 * x + B] = (guchar)(255 * src[3 * x + 2]); \
+        } \
+\
+      dest_data += dest_stride; \
+      src_data += src_stride; \
+    } \
+}
+
+SWIZZLE_FLOAT_OPAQUE(3,2,1,0)
+SWIZZLE_FLOAT_OPAQUE(0,1,2,3)
+SWIZZLE_FLOAT_OPAQUE(3,0,1,2)
+
+#define SWIZZLE_FLOAT(A,R,G,B) \
+static void \
+convert_float_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++) \
+    { \
+      float *src = (float *)src_data; \
+      for (x = 0; x < width; x++) \
+        { \
+          dest_data[4 * x + A] = (guchar)(255 * src[3 * x + 0]); \
+          dest_data[4 * x + R] = (guchar)(255 * src[3 * x + 1]); \
+          dest_data[4 * x + G] = (guchar)(255 * src[3 * x + 2]); \
+          dest_data[4 * x + B] = (guchar)(255 * src[3 * x + 3]); \
+        } \
+\
+      dest_data += dest_stride; \
+      src_data += src_stride; \
+    } \
+}
+
+SWIZZLE_FLOAT(3,2,1,0)
+SWIZZLE_FLOAT(0,1,2,3)
+SWIZZLE_FLOAT(3,0,1,2)
+
 typedef void (* ConversionFunc) (guchar       *dest_data,
                                  gsize         dest_stride,
                                  const guchar *src_data,
@@ -421,7 +489,9 @@ static ConversionFunc converters[GDK_MEMORY_N_FORMATS][3] =
   { convert_swizzle_opaque_3012, convert_swizzle_opaque_0321, convert_swizzle_opaque_3210 },
   { 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 }
+  { convert_fp16_swizzle_3210, convert_fp16_swizzle_0123, convert_fp16_swizzle_3012 },
+  { convert_float_swizzle_opaque_3210, convert_float_swizzle_opaque_0123, convert_float_swizzle_opaque_3012 
},
+  { convert_float_swizzle_3210, convert_float_swizzle_0123, convert_float_swizzle_3012 }
 };
 
 void
diff --git a/gdk/gdkmemorytexture.h b/gdk/gdkmemorytexture.h
index d9a0788051..f38845cdb0 100644
--- a/gdk/gdkmemorytexture.h
+++ b/gdk/gdkmemorytexture.h
@@ -50,6 +50,11 @@ G_BEGIN_DECLS
  * @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_B32G32R32_FLOAT: 3 float values; for blue, green, red.
+ *   The data is opaque. Since 4.6
+ * @GDK_MEMORY_R32G32B32A32_FLOAT_PREMULTIPLIED: 4 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.
  *
@@ -80,6 +85,8 @@ typedef enum {
   GDK_MEMORY_R16G16B16A16_PREMULTIPLIED,
   GDK_MEMORY_R16G16B16_FLOAT,
   GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED,
+  GDK_MEMORY_R32G32B32_FLOAT,
+  GDK_MEMORY_R32G32B32A32_FLOAT_PREMULTIPLIED,
 
   GDK_MEMORY_N_FORMATS
 } GdkMemoryFormat;
diff --git a/testsuite/gdk/memorytexture.c b/testsuite/gdk/memorytexture.c
index 099cbacdf1..92f9d8f472 100644
--- a/testsuite/gdk/memorytexture.c
+++ b/testsuite/gdk/memorytexture.c
@@ -189,7 +189,8 @@ main (int argc, char *argv[])
 
   for (format = 0; format < GDK_MEMORY_N_FORMATS; format++)
     {
-      if (format == GDK_MEMORY_R16G16B16_FLOAT)
+      if (format == GDK_MEMORY_R16G16B16_FLOAT ||
+          format == GDK_MEMORY_R32G32B32_FLOAT)
         continue;
 
       for (color = 0; color < N_COLORS; color++)