[retro-gtk/wip/aplazas/gl-display] add CRT video filter type

[Adrien Plazas <aplazas src gnome org>]

commit 5ef15b35486180e36bf1edaa6010bf2442405418
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Wed Nov 15 15:14:52 2017 +0100

    add CRT video filter type

 retro-gtk/retro-gl-display.c   |   80 ++++++++++++++++++++++++---------------
 retro-gtk/retro-video-filter.c |    1 +
 retro-gtk/retro-video-filter.h |    2 +
 3 files changed, 52 insertions(+), 31 deletions(-)
---
diff --git a/retro-gtk/retro-gl-display.c b/retro-gtk/retro-gl-display.c
index 19ddcee..a03b88e 100644
--- a/retro-gtk/retro-gl-display.c
+++ b/retro-gtk/retro-gl-display.c
@@ -93,12 +93,58 @@ static GLuint elements[] = {
 };
 
 static void
+prepare_shader_program (RetroGLDisplay *self)
+{
+  const gchar *uri;
+  GLuint program;
+  GLint attrib;
+
+  if (self->glsl_filter != NULL)
+    return;
+
+  switch (self->filter) {
+  case RETRO_VIDEO_FILTER_SHARP:
+    uri = "resource:///org/gnome/Retro/glsl-filters/sharp.filter";
+
+    break;
+  case RETRO_VIDEO_FILTER_SMOOTH:
+  default:
+    uri = "resource:///org/gnome/Retro/glsl-filters/bicubic.filter";
+
+    break;
+  case RETRO_VIDEO_FILTER_CRT:
+  default:
+    uri = "resource:///org/gnome/Retro/glsl-filters/crt-simple.filter";
+
+    break;
+  }
+
+  self->glsl_filter = retro_glsl_filter_new (uri, NULL);
+  program = retro_glsl_filter_create_program (self->glsl_filter);
+
+  glUseProgram (program);
+  attrib = glGetAttribLocation (program, "position");
+  glVertexAttribPointer (attrib, sizeof (((RetroVertex *) NULL)->position) / sizeof (float), GL_FLOAT, 
GL_FALSE,
+                         sizeof (RetroVertex), offsetof (RetroVertex, position));
+  glEnableVertexAttribArray (attrib);
+
+  attrib = glGetAttribLocation (program, "texCoord");
+  glVertexAttribPointer (attrib, sizeof (((RetroVertex *) NULL)->texture_coordinates) / sizeof (float), 
GL_FLOAT, GL_FALSE,
+                         sizeof (RetroVertex), offsetof (RetroVertex, texture_coordinates));
+  glEnableVertexAttribArray (attrib);
+
+  glGenTextures (1, &self->texture);
+  glBindTexture (GL_TEXTURE_2D, self->texture);
+
+  self->shader_program = program;
+}
+
+static void
 retro_gl_display_realize (RetroGLDisplay *self)
 {
   GLuint vertex_buffer_object;
   GLuint vertex_array_object;
   GLuint element_buffer_object;
-  GLuint program;
 
   gtk_gl_area_make_current (GTK_GL_AREA (self));
 
@@ -113,24 +159,7 @@ retro_gl_display_realize (RetroGLDisplay *self)
   glBindBuffer (GL_ELEMENT_ARRAY_BUFFER, element_buffer_object);
   glBufferData (GL_ELEMENT_ARRAY_BUFFER, sizeof (elements), elements, GL_STATIC_DRAW);
 
-  self->glsl_filter = retro_glsl_filter_new ("resource:///org/gnome/Retro/glsl-filters/crt-simple.filter", 
NULL);
-  program = retro_glsl_filter_create_program (self->glsl_filter);
-
-  glUseProgram (program);
-  GLint position_attrib = glGetAttribLocation (program, "position");
-  glVertexAttribPointer (position_attrib, sizeof (((RetroVertex *) NULL)->position) / sizeof (float), 
GL_FLOAT, GL_FALSE,
-                         sizeof (RetroVertex), offsetof (RetroVertex, position));
-  glEnableVertexAttribArray (position_attrib);
-
-  GLint texture_coordinates_attrib = glGetAttribLocation (program, "texCoord");
-  glVertexAttribPointer (texture_coordinates_attrib, sizeof (((RetroVertex *) NULL)->texture_coordinates) / 
sizeof (float), GL_FLOAT, GL_FALSE,
-                         sizeof (RetroVertex), offsetof (RetroVertex, texture_coordinates));
-  glEnableVertexAttribArray (texture_coordinates_attrib);
-
-  glGenTextures (1, &self->texture);
-  glBindTexture (GL_TEXTURE_2D, self->texture);
-
-  self->shader_program = program;
+  prepare_shader_program (self);
 }
 
 static void
@@ -166,7 +195,6 @@ retro_gl_display_render (RetroGLDisplay *self)
   gdouble h = 0.0;
   gdouble x = 0.0;
   gdouble y = 0.0;
-  GLenum filter;
   GLint relative_aspect_ratio;
   GLfloat source_width, source_height;
   GLfloat target_width, target_height;
@@ -176,17 +204,7 @@ retro_gl_display_render (RetroGLDisplay *self)
 
   retro_gl_display_get_video_box (self, &w, &h, &x, &y);
 
-  switch (self->filter) {
-  case RETRO_VIDEO_FILTER_SHARP:
-    filter = GL_NEAREST;
-
-    break;
-  default:
-  case RETRO_VIDEO_FILTER_SMOOTH:
-    filter = GL_LINEAR;
-
-    break;
-  }
+  prepare_shader_program (self);
 
   glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
diff --git a/retro-gtk/retro-video-filter.c b/retro-gtk/retro-video-filter.c
index cbff527..70e9c9c 100644
--- a/retro-gtk/retro-video-filter.c
+++ b/retro-gtk/retro-video-filter.c
@@ -41,6 +41,7 @@ retro_video_filter_get_type (void)
     static const GEnumValue values[] = {
       { RETRO_VIDEO_FILTER_SMOOTH, "RETRO_VIDEO_FILTER_SMOOTH", "smooth" },
       { RETRO_VIDEO_FILTER_SHARP, "RETRO_VIDEO_FILTER_SHARP", "sharp" },
+      { RETRO_VIDEO_FILTER_CRT, "RETRO_VIDEO_FILTER_CRT", "crt" },
       { 0, NULL, NULL },
     };
     GType type;
diff --git a/retro-gtk/retro-video-filter.h b/retro-gtk/retro-video-filter.h
index 7eb6f53..0926278 100644
--- a/retro-gtk/retro-video-filter.h
+++ b/retro-gtk/retro-video-filter.h
@@ -19,6 +19,7 @@ GType retro_video_filter_get_type (void) G_GNUC_CONST;
  * RetroVideoFilter:
  * @RETRO_VIDEO_FILTER_SMOOTH: a smooth but blurry video filer
  * @RETRO_VIDEO_FILTER_SHARP: a sharp video filter showing every pixel
+ * @RETRO_VIDEO_FILTER_CRT: a video filter mimicking CRT screens
  *
  * Represents the filters that can be applied to the video output.
  */
@@ -26,6 +27,7 @@ typedef enum
 {
   RETRO_VIDEO_FILTER_SMOOTH,
   RETRO_VIDEO_FILTER_SHARP,
+  RETRO_VIDEO_FILTER_CRT,
 } RetroVideoFilter;
 
 RetroVideoFilter retro_video_filter_from_string (const gchar *filter);