[gtk+/wip/ebassi/gsk-renderer: 94/194] gsk: Add ShaderBuilder

[Emmanuele Bassi <ebassi src gnome org>]

commit ebc1283221d0b62cba3aaa13e1658952a41d71e6
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Sun Jul 3 20:04:40 2016 +0100

    gsk: Add ShaderBuilder
    
    GskShaderBuilder is an ancillary, private type that deals with the
    internals of taking GLSL shaders from resources and building them,
    with the additional feature of being able to compose shaders from a
    common preamble, as well as adding conditional defines (useful for
    enabling debugging code in the shaders themselves).

 gsk/Makefile.am               |    6 +-
 gsk/gskshaderbuilder.c        |  359 +++++++++++++++++++++++++++++++++++++++++
 gsk/gskshaderbuilderprivate.h |   45 +++++
 3 files changed, 408 insertions(+), 2 deletions(-)
---
diff --git a/gsk/Makefile.am b/gsk/Makefile.am
index d3efb7c..7edabe3 100644
--- a/gsk/Makefile.am
+++ b/gsk/Makefile.am
@@ -37,9 +37,10 @@ gsk_private_source_h = \
        gskcairorendererprivate.h \
        gskdebugprivate.h \
        gskglrendererprivate.h \
+       gskprivate.h \
        gskrendererprivate.h \
        gskrendernodeprivate.h \
-       gskprivate.h
+       gskshaderbuilderprivate.h
 gsk_private_source_c = \
        gskprivate.c
 gsk_built_source_h = \
@@ -54,7 +55,8 @@ gsk_source_c = \
        gskglrenderer.c \
        gskrenderer.c \
        gskrendernode.c \
-       gskrendernodeiter.c
+       gskrendernodeiter.c \
+       gskshaderbuilder.c
 
 all_sources = \
        $(gsk_public_source_h) \
diff --git a/gsk/gskshaderbuilder.c b/gsk/gskshaderbuilder.c
new file mode 100644
index 0000000..16a0e1e
--- /dev/null
+++ b/gsk/gskshaderbuilder.c
@@ -0,0 +1,359 @@
+#include "config.h"
+
+#include "gskshaderbuilderprivate.h"
+
+#include <gdk/gdk.h>
+#include <epoxy/gl.h>
+
+struct _GskShaderBuilder
+{
+  GObject parent_instance;
+
+  char *resource_base_path;
+
+  int version;
+
+  int program_id;
+
+  GPtrArray *defines;
+  GPtrArray *uniforms;
+  GPtrArray *attributes;
+
+  GHashTable *uniform_locations;
+  GHashTable *attribute_locations;
+};
+
+G_DEFINE_TYPE (GskShaderBuilder, gsk_shader_builder, G_TYPE_OBJECT)
+
+static void
+gsk_shader_builder_finalize (GObject *gobject)
+{
+  GskShaderBuilder *self = GSK_SHADER_BUILDER (gobject);
+
+  g_free (self->resource_base_path);
+
+  g_clear_pointer (&self->defines, g_ptr_array_unref);
+  g_clear_pointer (&self->uniforms, g_ptr_array_unref);
+  g_clear_pointer (&self->attributes, g_ptr_array_unref);
+
+  g_clear_pointer (&self->uniform_locations, g_hash_table_unref);
+  g_clear_pointer (&self->attribute_locations, g_hash_table_unref);
+
+  G_OBJECT_CLASS (gsk_shader_builder_parent_class)->finalize (gobject);
+}
+
+static void
+gsk_shader_builder_class_init (GskShaderBuilderClass *klass)
+{
+  G_OBJECT_CLASS (klass)->finalize = gsk_shader_builder_finalize;
+}
+
+static void
+gsk_shader_builder_init (GskShaderBuilder *self)
+{
+  self->defines = g_ptr_array_new_with_free_func (g_free);
+  self->uniforms = g_ptr_array_new_with_free_func (g_free);
+  self->attributes = g_ptr_array_new_with_free_func (g_free);
+
+  self->uniform_locations = g_hash_table_new (g_direct_hash, g_direct_equal);
+  self->attribute_locations = g_hash_table_new (g_direct_hash, g_direct_equal);
+}
+
+GskShaderBuilder *
+gsk_shader_builder_new (void)
+{
+  return g_object_new (GSK_TYPE_SHADER_BUILDER, NULL);
+}
+
+void
+gsk_shader_builder_set_resource_base_path (GskShaderBuilder *builder,
+                                           const char       *base_path)
+{
+  g_return_if_fail (GSK_IS_SHADER_BUILDER (builder));
+
+  g_free (builder->resource_base_path);
+  builder->resource_base_path = g_strdup (base_path);
+}
+
+void
+gsk_shader_builder_set_version (GskShaderBuilder *builder,
+                                int               version)
+{
+  g_return_if_fail (GSK_IS_SHADER_BUILDER (builder));
+
+  builder->version = version;
+}
+
+void
+gsk_shader_builder_add_define (GskShaderBuilder *builder,
+                               const char       *define_name,
+                               const char       *define_value)
+{
+  g_return_if_fail (GSK_IS_SHADER_BUILDER (builder));
+  g_return_if_fail (define_name != NULL && *define_name != '\0');
+  g_return_if_fail (define_value != NULL && *define_name != '\0');
+
+  g_ptr_array_add (builder->defines, g_strdup (define_name));
+  g_ptr_array_add (builder->defines, g_strdup (define_value));
+}
+
+GQuark
+gsk_shader_builder_add_uniform (GskShaderBuilder *builder,
+                                const char       *uniform_name)
+{
+  g_return_val_if_fail (GSK_IS_SHADER_BUILDER (builder), 0);
+  g_return_val_if_fail (uniform_name != NULL, 0);
+
+  g_ptr_array_add (builder->uniforms, g_strdup (uniform_name));
+
+  return g_quark_from_string (uniform_name);
+}
+
+GQuark
+gsk_shader_builder_add_attribute (GskShaderBuilder *builder,
+                                  const char       *attribute_name)
+{
+  g_return_val_if_fail (GSK_IS_SHADER_BUILDER (builder), 0);
+  g_return_val_if_fail (attribute_name != NULL, 0);
+
+  g_ptr_array_add (builder->attributes, g_strdup (attribute_name));
+
+  return g_quark_from_string (attribute_name);
+}
+
+static gboolean
+lookup_shader_code (GString *code,
+                    const char *base_path,
+                    const char *shader_file,
+                    GError **error)
+{
+  GBytes *source;
+  char *path;
+
+  if (base_path != NULL)
+    path = g_build_filename (base_path, shader_file, NULL);
+  else
+    path = g_strdup (shader_file);
+
+  source = g_resources_lookup_data (path, 0, error);
+  g_free (path);
+
+  if (source == NULL)
+    return FALSE;
+
+  g_string_append (code, g_bytes_get_data (source, NULL));
+
+  g_bytes_unref (source);
+
+  return TRUE;
+}
+
+int
+gsk_shader_builder_compile_shader (GskShaderBuilder *builder,
+                                   int               shader_type,
+                                   const char       *shader_preamble,
+                                   const char       *shader_source,
+                                   GError          **error)
+{
+  GString *code;
+  char *source;
+  int shader_id;
+  int status;
+  int i;
+
+  g_return_val_if_fail (GSK_IS_SHADER_BUILDER (builder), -1);
+  g_return_val_if_fail (shader_source != NULL, -1);
+
+  code = g_string_new (NULL);
+
+  if (builder->version > 0)
+    {
+      g_string_append_printf (code, "#version %d\n", builder->version);
+      g_string_append_c (code, '\n');
+    }
+
+  for (i = 0; i < builder->defines->len; i += 2)
+    {
+      const char *name = g_ptr_array_index (builder->defines, i);
+      const char *value = g_ptr_array_index (builder->defines, i + 1);
+
+      g_string_append (code, "#define");
+      g_string_append_c (code, ' ');
+      g_string_append (code, name);
+      g_string_append_c (code, ' ');
+      g_string_append (code, value);
+      g_string_append_c (code, '\n');
+
+      if (i == builder->defines->len - 2)
+        g_string_append_c (code, '\n');
+    }
+
+  if (!lookup_shader_code (code, builder->resource_base_path, shader_preamble, error))
+    {
+      g_string_free (code, TRUE);
+      return -1;
+    }
+
+  if (!lookup_shader_code (code, builder->resource_base_path, shader_source, error))
+    {
+      g_string_free (code, TRUE);
+      return -1;
+    }
+
+  source = g_string_free (code, FALSE);
+
+  shader_id = glCreateShader (shader_type);
+  glShaderSource (shader_id, 1, (const GLchar **) &source, NULL);
+  glCompileShader (shader_id);
+
+  g_free (source);
+
+  glGetShaderiv (shader_id, GL_COMPILE_STATUS, &status);
+  if (status == GL_FALSE)
+    {
+      int log_len;
+      char *buffer;
+
+      glGetShaderiv (shader_id, GL_INFO_LOG_LENGTH, &log_len);
+
+      buffer = g_malloc0 (log_len + 1);
+      glGetShaderInfoLog (shader_id, log_len, NULL, buffer);
+
+      g_set_error (error, GDK_GL_ERROR, GDK_GL_ERROR_COMPILATION_FAILED,
+                   "Compilation failure in %s shader:\n%s",
+                   shader_type == GL_VERTEX_SHADER ? "vertex" : "fragment",
+                   buffer);
+      g_free (buffer);
+
+      glDeleteShader (shader_id);
+
+      return -1;
+    }
+
+  return shader_id;
+}
+
+static void
+gsk_shader_builder_cache_uniforms (GskShaderBuilder *builder,
+                                   int               program_id)
+{
+  int i;
+
+  for (i = 0; i < builder->uniforms->len; i++)
+    {
+      const char *uniform = g_ptr_array_index (builder->uniforms, i);
+      int loc = glGetUniformLocation (program_id, uniform);
+
+      g_hash_table_insert (builder->uniform_locations,
+                           GINT_TO_POINTER (g_quark_from_string (uniform)),
+                           GINT_TO_POINTER (loc));
+    }
+}
+
+static void
+gsk_shader_builder_cache_attributes (GskShaderBuilder *builder,
+                                     int               program_id)
+{
+  int i;
+
+  for (i = 0; i < builder->attributes->len; i++)
+    {
+      const char *attribute = g_ptr_array_index (builder->attributes, i);
+      int loc = glGetAttribLocation (program_id, attribute);
+
+      g_hash_table_insert (builder->attribute_locations,
+                           GINT_TO_POINTER (g_quark_from_string (attribute)),
+                           GINT_TO_POINTER (loc));
+    }
+}
+
+int
+gsk_shader_builder_create_program (GskShaderBuilder *builder,
+                                   int               vertex_id,
+                                   int               fragment_id,
+                                   GError          **error)
+{
+  int program_id;
+  int status;
+
+  g_return_val_if_fail (GSK_IS_SHADER_BUILDER (builder), -1);
+  g_return_val_if_fail (vertex_id > 0, -1);
+  g_return_val_if_fail (fragment_id > 0, -1);
+
+  program_id = glCreateProgram ();
+  glAttachShader (program_id, vertex_id);
+  glAttachShader (program_id, fragment_id);
+  glLinkProgram (program_id);
+
+  glGetProgramiv (program_id, GL_LINK_STATUS, &status);
+  if (status == GL_FALSE)
+    {
+      char *buffer = NULL;
+      int log_len = 0;
+
+      glGetProgramiv (program_id, GL_INFO_LOG_LENGTH, &log_len);
+
+      buffer = g_malloc0 (log_len + 1);
+      glGetProgramInfoLog (program_id, log_len, NULL, buffer);
+
+      g_set_error (error, GDK_GL_ERROR, GDK_GL_ERROR_LINK_FAILED,
+                   "Linking failure in shader:\n%s", buffer);
+      g_free (buffer);
+
+      glDeleteProgram (program_id);
+      program_id = -1;
+
+      goto out;
+    }
+
+  gsk_shader_builder_cache_uniforms (builder, program_id);
+  gsk_shader_builder_cache_attributes (builder, program_id);
+
+  builder->program_id = program_id;
+
+out:
+  glDetachShader (program_id, vertex_id);
+  glDetachShader (program_id, fragment_id);
+
+  return program_id;
+}
+
+int
+gsk_shader_builder_get_uniform_location (GskShaderBuilder *builder,
+                                         GQuark            uniform_quark)
+{
+  gpointer loc_p = NULL;
+
+  g_return_val_if_fail (GSK_IS_SHADER_BUILDER (builder), -1);
+
+  if (builder->program_id < 0)
+    return -1;
+
+  if (builder->uniforms->len == 0)
+    return -1;
+
+  if (g_hash_table_lookup_extended (builder->uniform_locations, GINT_TO_POINTER (uniform_quark), NULL, 
&loc_p))
+    return GPOINTER_TO_INT (loc_p);
+
+  return -1;
+}
+
+int
+gsk_shader_builder_get_attribute_location (GskShaderBuilder *builder,
+                                           GQuark            attribute_quark)
+{
+  gpointer loc_p = NULL;
+
+  g_return_val_if_fail (GSK_IS_SHADER_BUILDER (builder), -1);
+
+  if (builder->program_id < 0)
+    return -1;
+
+  if (builder->attributes->len == 0)
+    return -1;
+
+  if (g_hash_table_lookup_extended (builder->attribute_locations, GINT_TO_POINTER (attribute_quark), NULL, 
&loc_p))
+    return GPOINTER_TO_INT (loc_p);
+
+  return -1;
+}
diff --git a/gsk/gskshaderbuilderprivate.h b/gsk/gskshaderbuilderprivate.h
new file mode 100644
index 0000000..f5f7ff8
--- /dev/null
+++ b/gsk/gskshaderbuilderprivate.h
@@ -0,0 +1,45 @@
+#ifndef __GSK_SHADER_BUILDER_PRIVATE_H__
+#define __GSK_SHADER_BUILDER_PRIVATE_H__
+
+#include <gdk/gdk.h>
+#include <graphene.h>
+
+G_BEGIN_DECLS
+
+#define GSK_TYPE_SHADER_BUILDER (gsk_shader_builder_get_type ())
+
+G_DECLARE_FINAL_TYPE (GskShaderBuilder, gsk_shader_builder, GSK, SHADER_BUILDER, GObject)
+
+GskShaderBuilder *      gsk_shader_builder_new                          (void);
+
+void                    gsk_shader_builder_set_version                  (GskShaderBuilder *builder,
+                                                                         int               version);
+void                    gsk_shader_builder_set_resource_base_path       (GskShaderBuilder *builder,
+                                                                         const char       *base_path);
+
+GQuark                  gsk_shader_builder_add_uniform                  (GskShaderBuilder *builder,
+                                                                         const char       *uniform_name);
+GQuark                  gsk_shader_builder_add_attribute                (GskShaderBuilder *builder,
+                                                                         const char       *attribute_name);
+void                    gsk_shader_builder_add_define                   (GskShaderBuilder *builder,
+                                                                         const char       *define_name,
+                                                                         const char       *define_value);
+
+int                     gsk_shader_builder_compile_shader               (GskShaderBuilder *builder,
+                                                                         int               shader_type,
+                                                                         const char       *shader_preamble,
+                                                                         const char       *shader_source,
+                                                                         GError          **error);
+int                     gsk_shader_builder_create_program               (GskShaderBuilder *builder,
+                                                                         int               vertex_id,
+                                                                         int               fragment_id,
+                                                                         GError          **error);
+
+int                     gsk_shader_builder_get_uniform_location         (GskShaderBuilder *builder,
+                                                                         GQuark            uniform_quark);
+int                     gsk_shader_builder_get_attribute_location       (GskShaderBuilder *builder,
+                                                                         GQuark            attribute_quark);
+
+G_END_DECLS
+
+#endif /* __GSK_SHADER_BUILDER_PRIVATE_H__ */