From bd5f0214bd50e9d7ddbc2cc1c2d685d705483dcc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julius=20Range-L=C3=BCdemann?= <julius.range@gmail.com>
Date: Wed, 13 May 2026 19:18:46 +0200
Subject: [PATCH] Use gl_VertexID for OpenGL

gl_VertexIndex is only available for vulkan targets, whereas gl_VertexID
is only available for opengl.
---
 Shaders/VertexShader.glsl | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Shaders/VertexShader.glsl b/Shaders/VertexShader.glsl
index b2f1d36..a49bb89 100644
--- a/Shaders/VertexShader.glsl
+++ b/Shaders/VertexShader.glsl
@@ -22,7 +22,11 @@ layout(location = 1) out flat vec3 o_Normal;
 layout(location = 2) out flat vec3 o_Color;
 void main() {
     gl_Position = modelViewProj * a_Positions;
+#ifdef VULKAN
     int face = gl_VertexIndex / 6;
+#else
+    int face = gl_VertexID / 6;
+#endif
     o_TexCoord = uvec2(face, 0);
     o_Normal = (model * normals[face]).xyz;
     o_Color = color.rgb;