bugfix(bgfx): Sample the scene composite the right way up on GLES

The composite pass reads the scene render target back to the swapchain with a
fullscreen triangle. Render targets are bottom-left origin on GLES and WebGL but
top-left on DX11 and Metal, and nothing accounted for that: the vertex shader
built one fixed set of texture coordinates and the backend passed a hardcoded 0
where the flip flag belongs.

So everything that goes through the composite - the whole 3D scene - came out
vertically mirrored on those renderers, while the UI, which draws straight to the
swapchain, stayed upright. That reads as "the game is upside down but the menus
are not".

Carry the flag in u_postTexelSize.z again, from bgfx's originBottomLeft cap, and
flip V in the vertex shader when it is set. DX11 and Metal report false and pass
0.0, so they are byte-for-byte unaffected.

Author: githubawn

Core/Libraries/Source/WWVegas/WW3D2/BgfxBackend.cpp

@@ -4045,10 +4045,15 @@ static void SubmitSceneComposite()
     // Texel size of the (supersampled) scene color the composite samples.
     const float texW = g_device.sceneRenderWidth > 0 ? static_cast<float>(g_device.sceneRenderWidth) : static_cast<float>(g_device.width);
     const float texH = g_device.sceneRenderHeight > 0 ? static_cast<float>(g_device.sceneRenderHeight) : static_cast<float>(g_device.height);
+    // TheSuperHackers @bugfix githubawn 30/07/2026 .z carries the V-flip flag for the
+    // composite. Render targets are bottom-left origin on GLES and WebGL but top-left on
+    // DX11 and Metal, so without it the whole 3D scene comes out of this pass upside down
+    // on those renderers, while the UI - drawn straight to the backbuffer - stays the right
+    // way up. The cap decides it, so DX11 and Metal pass 0.0 and are unaffected.
     const float postTexelSize[4] = {
         1.0f / texW,
         1.0f / texH,
-        0.0f,
+        bgfx::getCaps()->originBottomLeft ? 1.0f : 0.0f,
         0.0f
     };
     if (bgfx::isValid(g_uniforms.uPostParams))

Core/Libraries/Source/WWVegas/WW3D2/shaders/vs_scene_composite.sc

@@ -7,8 +7,21 @@ $output v_texcoord0
 
 #include <bgfx_shader.sh>
 
+// TheSuperHackers @bugfix githubawn 30/07/2026 u_postTexelSize.z carries a V-flip flag
+// (1.0 on bottom-left-origin renderers like GLES and WebGL, 0.0 on DX11 and Metal) so the
+// scene render target is sampled the right way up. Without it this pass hands back a
+// vertically mirrored scene on those renderers - the UI draws straight to the swapchain and
+// looks correct, which makes it read as "the game is upside down but the menus are not".
+uniform vec4 u_postTexelSize;
+
 void main()
 {
 	gl_Position = vec4(a_position, 1.0);
-	v_texcoord0 = vec2(a_position.x * 0.5 + 0.5, 0.5 - a_position.y * 0.5);
+	float u = a_position.x * 0.5 + 0.5;
+	float v = 0.5 - a_position.y * 0.5;
+	if (u_postTexelSize.z > 0.5)
+	{
+		v = 1.0 - v;
+	}
+	v_texcoord0 = vec2(u, v);
 }