[gtk+/wip/ebassi/gles: 108/113] gdk: Add GLES shaders

[Emmanuele Bassi <ebassi src gnome org>]

commit e9da51579c554257b8e1ae5fe77fe4963c4976df
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Fri Apr 22 13:52:49 2016 +0100

    gdk: Add GLES shaders
    
    We cannot use GL shaders with GLES.

 gdk/Makefile.am                          |    4 +++-
 gdk/gdkgl.c                              |   26 +++++++++++++++++++++++---
 gdk/resources/glsl/gles2-texture.fs.glsl |    7 +++++++
 gdk/resources/glsl/gles2-texture.vs.glsl |   10 ++++++++++
 4 files changed, 43 insertions(+), 4 deletions(-)
---
diff --git a/gdk/Makefile.am b/gdk/Makefile.am
index f33c8ae..0cb43ba 100644
--- a/gdk/Makefile.am
+++ b/gdk/Makefile.am
@@ -468,7 +468,9 @@ glsl_sources = \
        resources/glsl/gl2-texture-2d.fs.glsl \
        resources/glsl/gl2-texture-2d.fs.glsl \
        resources/glsl/gl2-texture-rect.vs.glsl \
-       resources/glsl/gl2-texture-rect.vs.glsl
+       resources/glsl/gl2-texture-rect.vs.glsl \
+       resources/glsl/gles2-texture.fs.glsl \
+       resources/glsl/gles2-texture.vs.glsl
 
 EXTRA_DIST += $(glsl_sources)
 CLEANFILES += gdk.gresource.xml
diff --git a/gdk/gdkgl.c b/gdk/gdkgl.c
index 155e8cd..748e80f 100644
--- a/gdk/gdkgl.c
+++ b/gdk/gdkgl.c
@@ -152,6 +152,21 @@ bind_vao (GdkGLContextPaintData *paint_data)
 }
 
 static void
+use_texture_gles_program (GdkGLContextPaintData *paint_data)
+{
+  if (paint_data->texture_2d_quad_program.program == 0)
+    make_program (&paint_data->texture_2d_quad_program,
+                  "/org/gtk/libgdk/glsl/gles2-texture.vs.glsl",
+                  "/org/gtk/libgdk/glsl/gles2-texture.fs.glsl");
+
+  if (paint_data->current_program != &paint_data->texture_2d_quad_program)
+    {
+      paint_data->current_program = &paint_data->texture_2d_quad_program;
+      glUseProgram (paint_data->current_program->program);
+    }
+}
+
+static void
 use_texture_2d_program (GdkGLContextPaintData *paint_data)
 {
   const char *vertex_shader_path = paint_data->is_legacy
@@ -213,10 +228,15 @@ gdk_gl_texture_quads (GdkGLContext *paint_context,
   if (paint_data->tmp_vertex_buffer == 0)
     glGenBuffers(1, &paint_data->tmp_vertex_buffer);
 
-  if (texture_target == GL_TEXTURE_RECTANGLE_ARB)
-    use_texture_rect_program (paint_data);
+  if (paint_data->use_es)
+    use_texture_gles_program (paint_data);
   else
-    use_texture_2d_program (paint_data);
+    {
+      if (texture_target == GL_TEXTURE_RECTANGLE_ARB)
+        use_texture_rect_program (paint_data);
+      else
+        use_texture_2d_program (paint_data);
+    }
 
   program = paint_data->current_program;
 
diff --git a/gdk/resources/glsl/gles2-texture.fs.glsl b/gdk/resources/glsl/gles2-texture.fs.glsl
new file mode 100644
index 0000000..a2a0415
--- /dev/null
+++ b/gdk/resources/glsl/gles2-texture.fs.glsl
@@ -0,0 +1,7 @@
+uniform sampler2D map;
+
+varying vec2 vUv;
+
+void main() {
+  gl_FragColor = texture2D(map, vUv);
+}
diff --git a/gdk/resources/glsl/gles2-texture.vs.glsl b/gdk/resources/glsl/gles2-texture.vs.glsl
new file mode 100644
index 0000000..0625cb3
--- /dev/null
+++ b/gdk/resources/glsl/gles2-texture.vs.glsl
@@ -0,0 +1,10 @@
+attribute vec2 position;
+attribute vec2 uv;
+
+varying vec2 vUv;
+
+void main() {
+  vUv = uv;
+
+  gl_Position = vec4(position, 0.0, 1.0);
+}