message: Better blend function
diff: @@ -353,7 +353,7 @@ void depth_compositor::composite_textures() const
  GLint active_texture = GL_TEXTURE0;
  GLuint bound_texture = 0;
  GLboolean blend = glIsEnabled(GL_BLEND);
  - GLenum sfactor = GL_SRC_ALPHA;
  + GLenum sfactor = GL_ONE;
  GLenum dfactor = GL_ONE_MINUS_SRC_ALPHA;
  GLboolean depth_test = GL_FALSE;
  glGetIntegerv(GL_ACTIVE_TEXTURE, &active_texture);
  @@ -363,7 +363,7 @@ void depth_compositor::composite_textures() const
  glGetIntegerv(GL_BLEND_DST, reinterpret_cast<GLint*>(&dfactor));
  - glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  + glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
  glEnable(GL_BLEND);
  glEnable(GL_DEPTH_TEST);
  @@ -445,7 +445,7 @@ void depth_compositor::display_color_texture() const
  GLint active_texture = GL_TEXTURE0;
  GLuint bound_texture = 0;
  GLboolean blend = glIsEnabled(GL_BLEND);
  - GLenum sfactor = GL_SRC_ALPHA;
  + GLenum sfactor = GL_ONE;
  GLenum dfactor = GL_ONE_MINUS_SRC_ALPHA;
  glGetIntegerv(GL_ACTIVE_TEXTURE, &active_texture);
  glGetIntegerv(GL_TEXTURE_BINDING_2D, reinterpret_cast<GLint*>(&bound_texture));
  @@ -453,7 +453,7 @@ void depth_compositor::display_color_texture() const
  glGetIntegerv(GL_BLEND_DST, reinterpret_cast<GLint*>(&dfactor));
  - glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  + glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
  glEnable(GL_BLEND);
  impl_->color_prog.enable(impl_->color_texture);
  