[gtk/matthiasc/color-profile-rebased: 29/46] gsk: Linearize gl textures

[Matthias Clasen <matthiasc src gnome org>]

commit 8fd17568f0acd37ac46c850e6bbe504e49bb9b36
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun May 8 13:32:01 2022 -0400

    gsk: Linearize gl textures
    
    GL textures are typically in non-linear sRGB,
    and in that case, we need to linearize them.

 gsk/gl/gskgldriver.c            | 142 ++++++++++++++++++++++++++++++++++++++--
 gsk/gl/gskglprograms.defs       |   3 +
 gsk/gl/resources/linearize.glsl |  22 +++++++
 gsk/meson.build                 |   1 +
 4 files changed, 164 insertions(+), 4 deletions(-)
---
diff --git a/gsk/gl/gskgldriver.c b/gsk/gl/gskgldriver.c
index cc6aad3a3b..0a19ef503d 100644
--- a/gsk/gl/gskgldriver.c
+++ b/gsk/gl/gskgldriver.c
@@ -40,6 +40,7 @@
 
 #include <gdk/gdkglcontextprivate.h>
 #include <gdk/gdkdisplayprivate.h>
+#include <gdk/gdkmemoryformatprivate.h>
 #include <gdk/gdkmemorytextureprivate.h>
 #include <gdk/gdkprofilerprivate.h>
 #include <gdk/gdktextureprivate.h>
@@ -684,6 +685,79 @@ gsk_gl_driver_cache_texture (GskGLDriver         *self,
   g_hash_table_insert (self->texture_id_to_key, GUINT_TO_POINTER (texture_id), k);
 }
 
+static void
+draw_offscreen (GskGLCommandQueue *command_queue,
+                float              min_x,
+                float              min_y,
+                float              max_x,
+                float              max_y)
+{
+  GskGLDrawVertex *vertices = gsk_gl_command_queue_add_vertices (command_queue);
+  float min_u = 0;
+  float min_v = 1;
+  float max_u = 1;
+  float max_v = 0;
+  guint16 c[4] = { FP16_ZERO, FP16_ZERO, FP16_ZERO, FP16_ZERO };
+
+  vertices[0] = (GskGLDrawVertex) { .position = { min_x, min_y }, .uv = { min_u, min_v }, .color = { c[0], 
c[1], c[2
+], c[3] } };
+  vertices[1] = (GskGLDrawVertex) { .position = { min_x, max_y }, .uv = { min_u, max_v }, .color = { c[0], 
c[1], c[2
+], c[3] } };
+  vertices[2] = (GskGLDrawVertex) { .position = { max_x, min_y }, .uv = { max_u, min_v }, .color = { c[0], 
c[1], c[2
+], c[3] } };
+  vertices[3] = (GskGLDrawVertex) { .position = { max_x, max_y }, .uv = { max_u, max_v }, .color = { c[0], 
c[1], c[2
+], c[3] } };
+  vertices[4] = (GskGLDrawVertex) { .position = { min_x, max_y }, .uv = { min_u, max_v }, .color = { c[0], 
c[1], c[2
+], c[3] } };
+  vertices[5] = (GskGLDrawVertex) { .position = { max_x, min_y }, .uv = { max_u, min_v }, .color = { c[0], 
c[1], c[2], c[3] } };
+}
+
+static void
+set_viewport_for_size (GskGLProgram *program,
+                         float         width,
+                         float         height)
+{
+  float viewport[4] = { 0, 0, width, height };
+
+  gsk_gl_uniform_state_set4fv (program->uniforms,
+                               program->program_info,
+                               UNIFORM_SHARED_VIEWPORT, 0,
+                               1,
+                               (const float *)&viewport);
+}
+
+#define ORTHO_NEAR_PLANE   -10000
+#define ORTHO_FAR_PLANE     10000
+
+static void
+set_projection_for_size (GskGLProgram *program,
+                       float            width,
+                       float            height)
+{
+  graphene_matrix_t projection;
+
+  graphene_matrix_init_ortho (&projection, 0, width, 0, height, ORTHO_NEAR_PLANE, ORTHO_FAR_PLANE);
+  graphene_matrix_scale (&projection, 1, -1, 1);
+
+  gsk_gl_uniform_state_set_matrix (program->uniforms,
+                                   program->program_info,
+                                   UNIFORM_SHARED_PROJECTION, 0,
+                                   &projection);
+}
+
+static void
+reset_modelview (GskGLProgram *program)
+{
+  graphene_matrix_t modelview;
+
+  graphene_matrix_init_identity (&modelview);
+
+  gsk_gl_uniform_state_set_matrix (program->uniforms,
+                                   program->program_info,
+                                   UNIFORM_SHARED_MODELVIEW, 0,
+                                   &modelview);
+}
+
 /**
  * gsk_gl_driver_load_texture:
  * @self: a `GdkTexture`
@@ -714,9 +788,9 @@ gsk_gl_driver_load_texture (GskGLDriver *self,
                             int          mag_filter)
 {
   GdkGLContext *context;
-  GdkMemoryTexture *downloaded_texture;
+  GdkMemoryTexture *downloaded_texture = NULL;
+  guint texture_id = 0;
   GskGLTexture *t;
-  guint texture_id;
   int height;
   int width;
   int format;
@@ -726,8 +800,10 @@ gsk_gl_driver_load_texture (GskGLDriver *self,
   g_return_val_if_fail (GSK_IS_GL_COMMAND_QUEUE (self->command_queue), 0);
 
   context = self->command_queue->context;
+  width = gdk_texture_get_width (texture);
+  height = gdk_texture_get_height (texture);
 
-  format = GL_RGBA8;
+  format = gdk_memory_format_prefers_high_depth (gdk_texture_get_format (texture)) ? GL_RGBA16F : GL_RGBA8;
 
   if (GDK_IS_GL_TEXTURE (texture))
     {
@@ -736,8 +812,66 @@ gsk_gl_driver_load_texture (GskGLDriver *self,
 
       if (gdk_gl_context_is_shared (context, texture_context))
         {
+          guint gl_texture_id;
+
+          gl_texture_id = gdk_gl_texture_get_id (gl_texture);
+
           /* A GL texture from the same GL context is a simple task... */
-          return gdk_gl_texture_get_id (gl_texture);
+          if (gdk_color_profile_is_linear (gdk_texture_get_color_profile (texture)))
+            {
+              return gl_texture_id;
+            }
+          else
+            {
+              GskGLRenderTarget *target;
+              guint prev_fbo;
+
+              /* The GL texture isn't linear sRGB, so we need to convert
+               * it before we can use it. For now, we just assume that it
+               * is nonlinear sRGB. Eventually, we should figure out how
+               * to convert from other color spaces to linear sRGB
+               */
+              gdk_gl_context_make_current (context);
+
+              gsk_gl_driver_create_render_target (self,
+                                                  width, height,
+                                                  format,
+                                                  min_filter, mag_filter,
+                                                  &target);
+
+              prev_fbo = gsk_gl_command_queue_bind_framebuffer (self->command_queue, target->framebuffer_id);
+              gsk_gl_command_queue_clear (self->command_queue, 0, &GRAPHENE_RECT_INIT (0, 0, width, height));
+
+              gsk_gl_command_queue_begin_draw (self->command_queue,
+                                               self->linearize_no_clip->program_info,
+                                               width, height);
+
+              set_projection_for_size (self->linearize_no_clip, width, height);
+              set_viewport_for_size (self->linearize_no_clip, width, height);
+              reset_modelview (self->linearize_no_clip);
+
+              gsk_gl_program_set_uniform_texture (self->linearize_no_clip,
+                                                  UNIFORM_SHARED_SOURCE, 0,
+                                                  GL_TEXTURE_2D, GL_TEXTURE0, gl_texture_id);
+              draw_offscreen (self->command_queue, 0, 0, width, height);
+
+              gsk_gl_command_queue_end_draw (self->command_queue);
+
+              gsk_gl_command_queue_bind_framebuffer (self->command_queue, prev_fbo);
+
+              texture_id = gsk_gl_driver_release_render_target (self, target, FALSE);
+
+              t = gsk_gl_texture_new (texture_id,
+                                      width, height, format, min_filter, mag_filter,
+                                      self->current_frame_id);
+
+              /* Use gsk_gl_texture_free() as destroy notify here since we are
+               * not inserting this GskGLTexture into self->textures!
+               */
+              gdk_texture_set_render_data (texture, self, t, (GDestroyNotify)gsk_gl_texture_free);
+
+              return texture_id;
+            }
         }
       else
         {
diff --git a/gsk/gl/gskglprograms.defs b/gsk/gl/gskglprograms.defs
index db85f77cc2..9e820dc4ef 100644
--- a/gsk/gl/gskglprograms.defs
+++ b/gsk/gl/gskglprograms.defs
@@ -87,3 +87,6 @@ GSK_GL_DEFINE_PROGRAM (postprocessing,
                        GSK_GL_SHADER_SINGLE (GSK_GL_SHADER_RESOURCE ("postprocessing.glsl")),
                        GSK_GL_NO_UNIFORMS)
 
+GSK_GL_DEFINE_PROGRAM (linearize,
+                       GSK_GL_SHADER_SINGLE (GSK_GL_SHADER_RESOURCE ("linearize.glsl")),
+                       GSK_GL_NO_UNIFORMS)
diff --git a/gsk/gl/resources/linearize.glsl b/gsk/gl/resources/linearize.glsl
new file mode 100644
index 0000000000..7ae1e6998c
--- /dev/null
+++ b/gsk/gl/resources/linearize.glsl
@@ -0,0 +1,22 @@
+
+// VERTEX_SHADER:
+// linearize.glsl
+
+void main() {
+  gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
+
+  vUv = vec2(aUv.x, aUv.y);
+}
+
+// FRAGMENT_SHADER:
+// linearize.glsl
+
+void main() {
+  vec4 diffuse = GskTexture(u_source, vUv);
+
+  diffuse = gsk_unpremultiply(diffuse);
+  diffuse = gsk_srgb_to_linear(diffuse);
+  diffuse = gsk_premultiply(diffuse);
+
+  gskSetOutputColor(diffuse);
+}
diff --git a/gsk/meson.build b/gsk/meson.build
index 3b48660489..ca203eef85 100644
--- a/gsk/meson.build
+++ b/gsk/meson.build
@@ -20,6 +20,7 @@ gsk_private_gl_shaders = [
   'gl/resources/custom.glsl',
   'gl/resources/filled_border.glsl',
   'gl/resources/postprocessing.glsl',
+  'gl/resources/linearize.glsl',
 ]
 
 gsk_public_sources = files([