From f91d6b676c880d304f83f5dded1fed6e70cc6df1 Mon Sep 17 00:00:00 2001
From: Swung0x48 <swung0x48@outlook.com>
Date: Wed, 12 Aug 2026 08:12:32 -0400
Subject: [PATCH] [Fix] (MG_Impl): the per-stage atomic-counter-buffer limits
 answered GL_INVALID_ENUM instead of their zero

---
 MobileGL/MG_Impl/GLImpl/Getter/GL_Getter.cpp | 21 ++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/MobileGL/MG_Impl/GLImpl/Getter/GL_Getter.cpp b/MobileGL/MG_Impl/GLImpl/Getter/GL_Getter.cpp
index 7b2cad27..66f0d9c9 100644
--- a/MobileGL/MG_Impl/GLImpl/Getter/GL_Getter.cpp
+++ b/MobileGL/MG_Impl/GLImpl/Getter/GL_Getter.cpp
@@ -51,6 +51,15 @@ namespace MobileGL::MG_Impl::GLImpl {
         constexpr GLint kFrontendMaxTessControlAtomicCounters = 0;
         constexpr GLint kFrontendMaxTessEvaluationAtomicCounters = 0;
         constexpr GLint kFrontendMaxVertexAtomicCounters = 0;
+        // Zero counters means zero buffers to hold them. These have to be ANSWERED rather than
+        // left to the default INVALID_ENUM: a well-behaved application queries the limit exactly
+        // to find out that the stage cannot do this, and an error instead both leaves its output
+        // untouched (so it reads uninitialised memory and may conclude the opposite) and leaves a
+        // GL error pending that surfaces at whatever unrelated call checks next.
+        constexpr GLint kFrontendMaxGeometryAtomicCounterBuffers = 0;
+        constexpr GLint kFrontendMaxTessControlAtomicCounterBuffers = 0;
+        constexpr GLint kFrontendMaxTessEvaluationAtomicCounterBuffers = 0;
+        constexpr GLint kFrontendMaxVertexAtomicCounterBuffers = 0;
         // One atomic counter is a uint, and a buffer never has to hold more counters than the
         // combined limit the frontend advertises. GL 4.6 table 23.63 floors this at 32 bytes.
         constexpr GLint kFrontendMaxAtomicCounterBufferSize =
@@ -1458,6 +1467,9 @@ namespace MobileGL::MG_Impl::GLImpl {
         case GL_MAX_GEOMETRY_ATOMIC_COUNTERS:
             *params = kFrontendMaxGeometryAtomicCounters;
             return;
+        case GL_MAX_GEOMETRY_ATOMIC_COUNTER_BUFFERS:
+            *params = kFrontendMaxGeometryAtomicCounterBuffers;
+            return;
         case GL_MAX_GEOMETRY_SHADER_STORAGE_BLOCKS:
             *params = ClampStorageBlockCount(16); // TODO
             return;
@@ -1514,9 +1526,15 @@ namespace MobileGL::MG_Impl::GLImpl {
         case GL_MAX_TESS_CONTROL_ATOMIC_COUNTERS:
             *params = kFrontendMaxTessControlAtomicCounters;
             return;
+        case GL_MAX_TESS_CONTROL_ATOMIC_COUNTER_BUFFERS:
+            *params = kFrontendMaxTessControlAtomicCounterBuffers;
+            return;
         case GL_MAX_TESS_EVALUATION_ATOMIC_COUNTERS:
             *params = kFrontendMaxTessEvaluationAtomicCounters;
             return;
+        case GL_MAX_TESS_EVALUATION_ATOMIC_COUNTER_BUFFERS:
+            *params = kFrontendMaxTessEvaluationAtomicCounterBuffers;
+            return;
         case GL_MAX_TESS_CONTROL_IMAGE_UNIFORMS:
             *params = 0;
             return;
@@ -1544,6 +1562,9 @@ namespace MobileGL::MG_Impl::GLImpl {
         case GL_MAX_VERTEX_ATOMIC_COUNTERS:
             *params = kFrontendMaxVertexAtomicCounters;
             return;
+        case GL_MAX_VERTEX_ATOMIC_COUNTER_BUFFERS:
+            *params = kFrontendMaxVertexAtomicCounterBuffers;
+            return;
         case GL_MAX_VERTEX_IMAGE_UNIFORMS:
             *params = MG_Backend::pActiveBackendObject
                           ? MG_Backend::pActiveBackendObject->GetDynamicParameters().MaxVertexImageUniforms