orka: Revert changing origin of viewport to upper left corner

Without it, it would almost always require an extra render pass when
rendering using a frame graph to avoid textures being rendered upside
down.

docs/rendering/removed-features.md

@@ -54,20 +54,6 @@ Some conventions have changed to Vulkan's:
   The range of the depth of the clipping volume has been changed from
   the default of [-1, 1] to Vulkan's [0, 1].
 
-- **Origin of window coordinates is upper-left**.
-    The origin of the window coordinates has been changed to upper-left,
-    which is the origin used by other rendering APIs and windowing systems.
-
-    If a shader uses `:::glsl gl_FragCoord`, then you may need to redefine it:
-
-    ```glsl
-    layout(origin_upper_left) in vec4 gl_FragCoord;
-    ```
-
-    If the output on the screen is upside down, then render to a texture
-    instead and read it in some resolve or tonemapping pass that outputs
-    to the default framebuffer.
-
 ## Other removed features
 
 Over the years, OpenGL has accumulated a lot of functionality. Some of which

orka/data/shaders/effects/blur.frag

@@ -2,8 +2,6 @@
 
 #extension GL_ARB_shader_storage_buffer_object : require
 
-layout(origin_upper_left) in vec4 gl_FragCoord;
-
 //  SPDX-License-Identifier: Apache-2.0
 //
 //  Copyright (c) 2020 onox <[email protected]>
@@ -20,8 +18,6 @@ layout(origin_upper_left) in vec4 gl_FragCoord;
 //  See the License for the specific language governing permissions and
 //  limitations under the License.
 
-layout(origin_upper_left) in vec4 gl_FragCoord;
-
 uniform bool horizontal;
 
 layout(binding = 0) uniform sampler2DRect inputImage;

orka/src/egl/orka-contexts-egl.adb

@@ -88,7 +88,7 @@ package body Orka.Contexts.EGL is
       Orka.Debug.Set_Log_Messages (Enable => Flags.Debug);
 
       GL.Rasterization.Set_Provoking_Vertex (GL.Rasterization.First_Vertex);
-      GL.Viewports.Set_Clipping (GL.Viewports.Upper_Left, GL.Viewports.Zero_To_One);
+      GL.Viewports.Set_Clipping (GL.Viewports.Lower_Left, GL.Viewports.Zero_To_One);
 
       --  Enable reversed Z for better depth precision at great distances
       --  See https://developer.nvidia.com/content/depth-precision-visualized