[retro-gtk/wip/aplazas/gl-display: 7/10] gl-display: Use shaders

[Adrien Plazas <aplazas src gnome org>]

commit ab57ff0df7f6118d44f449d08061601a2cda48b8
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Sun Oct 15 09:36:05 2017 +0200

    gl-display: Use shaders

 retro-gtk/retro-gl-display.c |   33 +++++++++++++++++++++++++++++++++
 1 files changed, 33 insertions(+), 0 deletions(-)
---
diff --git a/retro-gtk/retro-gl-display.c b/retro-gtk/retro-gl-display.c
index 133bca4..ebbcf0b 100644
--- a/retro-gtk/retro-gl-display.c
+++ b/retro-gtk/retro-gl-display.c
@@ -14,6 +14,7 @@ struct _RetroGLDisplay
   gfloat aspect_ratio;
   gulong on_video_output_id;
 
+  GLuint shader_program;
   GLuint framebuffer;
 };
 
@@ -71,7 +72,37 @@ retro_gl_display_get_video_box (RetroGLDisplay *self,
 static void
 retro_gl_display_realize (RetroGLDisplay *self)
 {
+  GLuint vertex_shader;
+  GLuint fragment_shader;
+  GLuint shader_program;
+  GBytes *shader_source_bytes;
+  const gchar *shader_source;
+
   gtk_gl_area_make_current (GTK_GL_AREA (self));
+
+  // Prepare the vertex shader
+  shader_source_bytes = g_resources_lookup_data ("/org/gnome/Retro/retro-gl-display-vertex.glsl", 0, NULL);
+  shader_source = g_bytes_get_data (shader_source_bytes, NULL);
+  vertex_shader = glCreateShader (GL_VERTEX_SHADER);
+  glShaderSource (vertex_shader, 1, &shader_source, NULL);
+  glCompileShader (vertex_shader);
+  g_bytes_unref (shader_source_bytes);
+
+  // Prepare the fragment shader
+  shader_source_bytes = g_resources_lookup_data ("/org/gnome/Retro/retro-gl-display-fragment.glsl", 0, NULL);
+  shader_source = g_bytes_get_data (shader_source_bytes, NULL);
+  fragment_shader = glCreateShader (GL_FRAGMENT_SHADER);
+  glShaderSource (fragment_shader, 1, &shader_source, NULL);
+  glCompileShader (fragment_shader);
+  g_bytes_unref (shader_source_bytes);
+
+  // Prepare the shader program
+  shader_program = glCreateProgram();
+  glAttachShader (shader_program, vertex_shader);
+  glAttachShader (shader_program, fragment_shader);
+  glLinkProgram (shader_program);
+
+  self->shader_program = shader_program;
 }
 
 static void
@@ -80,6 +111,7 @@ retro_gl_display_unrealize (RetroGLDisplay *self)
   gtk_gl_area_make_current (GTK_GL_AREA (self));
 
   glDeleteFramebuffers (1, &self->framebuffer);
+  glDeleteProgram (self->shader_program);
 }
 
 static gboolean
@@ -108,6 +140,7 @@ retro_gl_display_render (RetroGLDisplay *self)
   }
 
   glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+  glUseProgram (self->shader_program);
 
   glBindFramebuffer (GL_READ_FRAMEBUFFER, self->framebuffer);
   glBlitFramebuffer (0, 0,