[retro-gtk/wip/aplazas/gl-errors] simplify shader management

[Adrien Plazas <aplazas src gnome org>]

commit 56fc9173d8fd137c0bdd2eba809a0a95d4815f85
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Thu Nov 16 12:26:44 2017 +0100

    simplify shader management

 retro-gtk/retro-glsl-filter.c |   42 ++++++++++++++++------------------------
 1 files changed, 17 insertions(+), 25 deletions(-)
---
diff --git a/retro-gtk/retro-glsl-filter.c b/retro-gtk/retro-glsl-filter.c
index 6e59fc8..7c534c7 100644
--- a/retro-gtk/retro-glsl-filter.c
+++ b/retro-gtk/retro-glsl-filter.c
@@ -9,8 +9,6 @@ struct _RetroGLSLFilter
   GBytes *fragment;
   GLenum wrap;
   GLenum filter;
-  GLuint vertex_shader;
-  GLuint fragment_shader;
   GLuint program;
 };
 
@@ -225,9 +223,8 @@ retro_glsl_filter_finalize (GObject *object)
     g_bytes_unref (self->vertex);
   if (self->fragment != NULL)
     g_bytes_unref (self->fragment);
-  glDeleteShader (self->vertex_shader);
-  glDeleteShader (self->fragment_shader);
   glDeleteProgram (self->program);
+  self->program = 0;
 
   G_OBJECT_CLASS (retro_glsl_filter_parent_class)->finalize (object);
 }
@@ -302,38 +299,33 @@ retro_glsl_filter_prepare_program (RetroGLSLFilter  *self,
   gint status;
   gint log_length;
   gchar *buffer;
+  GLuint vertex_shader;
+  GLuint fragment_shader;
   GError *inner_error = NULL;
 
   g_return_if_fail (RETRO_IS_GLSL_FILTER (self));
+  g_return_if_fail (self->program == 0);
 
-  self->vertex_shader = create_shader (self->vertex,
-                                       GL_VERTEX_SHADER,
-                                       &inner_error);
+  vertex_shader = create_shader (self->vertex, GL_VERTEX_SHADER, &inner_error);
   if (G_UNLIKELY (inner_error != NULL)) {
     g_propagate_error (error, inner_error);
-    self->vertex_shader = 0;
-    self->fragment_shader = 0;
     self->program = 0;
 
     return;
   }
 
-  self->fragment_shader = create_shader (self->fragment,
-                                         GL_FRAGMENT_SHADER,
-                                         &inner_error);
+  fragment_shader = create_shader (self->fragment, GL_FRAGMENT_SHADER, &inner_error);
   if (G_UNLIKELY (inner_error != NULL)) {
     g_propagate_error (error, inner_error);
-    glDeleteShader (self->vertex_shader);
-    self->vertex_shader = 0;
-    self->fragment_shader = 0;
+    glDeleteShader (vertex_shader);
     self->program = 0;
 
     return;
   }
 
   self->program = glCreateProgram();
-  glAttachShader (self->program, self->vertex_shader);
-  glAttachShader (self->program, self->fragment_shader);
+  glAttachShader (self->program, vertex_shader);
+  glAttachShader (self->program, fragment_shader);
   glLinkProgram (self->program);
 
   status = 0;
@@ -348,26 +340,23 @@ retro_glsl_filter_prepare_program (RetroGLSLFilter  *self,
                  "Linking failure in program: %s", buffer);
     g_free (buffer);
 
-    glDeleteShader (self->vertex_shader);
-    glDeleteShader (self->fragment_shader);
+    glDeleteShader (vertex_shader);
+    glDeleteShader (fragment_shader);
     glDeleteProgram (self->program);
-    self->vertex_shader = 0;
-    self->fragment_shader = 0;
     self->program = 0;
 
     return;
   }
 
-  glDetachShader (self->program, self->vertex_shader);
-  glDetachShader (self->program, self->fragment_shader);
-  self->vertex_shader = 0;
-  self->fragment_shader = 0;
+  glDetachShader (self->program, vertex_shader);
+  glDetachShader (self->program, fragment_shader);
 }
 
 void
 retro_glsl_filter_use_program (RetroGLSLFilter *self)
 {
   g_return_if_fail (RETRO_IS_GLSL_FILTER (self));
+  g_return_if_fail (self->program != 0);
 
   glUseProgram (self->program);
 }
@@ -384,6 +373,7 @@ retro_glsl_filter_set_attribute_pointer (RetroGLSLFilter *self,
   GLint location;
 
   g_return_if_fail (RETRO_IS_GLSL_FILTER (self));
+  g_return_if_fail (self->program != 0);
 
   location = glGetAttribLocation (self->program, name);
   glVertexAttribPointer (location, size, type, normalized, stride, pointer);
@@ -399,6 +389,7 @@ retro_glsl_filter_set_uniform_1f (RetroGLSLFilter *self,
   GLint location;
 
   g_return_if_fail (RETRO_IS_GLSL_FILTER (self));
+  g_return_if_fail (self->program != 0);
 
   location = glGetUniformLocation (self->program, name);
   glUniform1f (location, v0);
@@ -415,6 +406,7 @@ retro_glsl_filter_set_uniform_4f (RetroGLSLFilter *self,
   GLint location;
 
   g_return_if_fail (RETRO_IS_GLSL_FILTER (self));
+  g_return_if_fail (self->program != 0);
 
   location = glGetUniformLocation (self->program, name);
   glUniform4f (location, v0, v1, v2, v3);