[Feat, Test] (GLImpl, GLState): implement glBeginConditionalRender and discard the commands GL 4.6 10.9 names

MobileGL/MG_Impl/GLImpl/Drawing/GL_Drawing.cpp

@@ -326,10 +326,23 @@ namespace MobileGL::MG_Impl::GLImpl {
         }
     }
 
+    // GL 4.6 core 10.9: inside a conditional block whose predicate did not pass, the drawing
+    // commands, Clear, ClearBuffer* and the compute dispatches are DISCARDED. The gate sits on the
+    // wrappers that ISSUE the backend call rather than at the top of each entry point, so that
+    // everything a real driver would still do inside the block - argument validation and the
+    // errors it raises - happens exactly as it does outside one, and only the command itself is
+    // dropped. It is deliberately not on the frontend's transform-feedback accounting either:
+    // that mirrors what the capture stage would have written, and a conditional block around a
+    // capturing draw has no test coverage in either direction.
+    static Bool ConditionalRenderDiscardsCommand() {
+        return MG_State::pGLContext->ConditionalRenderDiscardsCommands();
+    }
+
     void Clear_Backend(GLbitfield mask) {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.Clear(mask);
     }
 
@@ -337,6 +350,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElements(mode, count, type, indices);
     }
 
@@ -345,6 +359,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawElements(mode, count, type, indices, drawcount);
     }
 
@@ -353,6 +368,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawElementsBaseVertex(mode, count, type, indices, drawcount,
                                                                           basevertex);
     }
@@ -361,6 +377,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawArrays(mode, first, count);
     }
 
@@ -368,6 +385,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawArrays(mode, first, count, drawcount);
     }
 
@@ -376,6 +394,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsBaseVertex(mode, count, type, indices, basevertex);
     }
 
@@ -384,6 +403,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawElementsIndirect(mode, type, indirect, drawcount, stride);
     }
 
@@ -391,6 +411,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawArraysIndirect(mode, indirect, drawcount, stride);
     }
 
@@ -399,6 +420,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawElementsIndirectCount(mode, type, indirect, drawcount,
                                                                              maxdrawcount, stride);
     }
@@ -408,6 +430,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawArraysIndirectCount(mode, indirect, drawcount, maxdrawcount,
                                                                            stride);
     }
@@ -417,6 +440,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawRangeElementsBaseVertex(mode, start, end, count, type, indices,
                                                                           basevertex);
     }
@@ -426,6 +450,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawRangeElements(mode, start, end, count, type, indices);
     }
 
@@ -435,6 +460,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsInstancedBaseVertexBaseInstance(
             mode, count, type, indices, instancecount, basevertex, baseinstance);
     }
@@ -444,6 +470,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsInstancedBaseVertex(mode, count, type, indices, instancecount,
                                                                               basevertex);
     }
@@ -453,6 +480,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsInstancedBaseInstance(mode, count, type, indices,
                                                                                 instancecount, baseinstance);
     }
@@ -462,6 +490,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsInstanced(mode, count, type, indices, instancecount);
     }
 
@@ -469,6 +498,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsIndirect(mode, type, indirect);
     }
     void DrawArraysInstancedBaseInstance_Backend(GLenum mode, GLint first, GLsizei count, GLsizei instancecount,
@@ -476,6 +506,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawArraysInstancedBaseInstance(mode, first, count, instancecount,
                                                                               baseinstance);
     }
@@ -484,6 +515,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawArraysInstanced(mode, first, count, instancecount);
     }
 
@@ -491,6 +523,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawArraysIndirect(mode, indirect);
     }
 
@@ -519,6 +552,9 @@ namespace MobileGL::MG_Impl::GLImpl {
                 return;
             }
         }
+        // GL 4.3 added both dispatches to the conditional-render set (GL 4.6 core 10.9), which is
+        // exactly what KHR-GL43.compute_shader.conditional-dispatching checks.
+        if (ConditionalRenderDiscardsCommand()) return;
         dispatchCompute(numGroupsX, numGroupsY, numGroupsZ);
     }
 
@@ -570,6 +606,7 @@ namespace MobileGL::MG_Impl::GLImpl {
             return;
         }
         if (!ValidateCurrentProgramForCompute(__func__)) return;
+        if (ConditionalRenderDiscardsCommand()) return;
         dispatchComputeIndirect(indirect);
     }
 

MobileGL/MG_Impl/GLImpl/Exporting/Definitions.cpp

@@ -725,8 +725,8 @@ DECLARE_GL_FUNCTION_STUB_HEAD(void, LoadName, GLuint name) DECLARE_GL_FUNCTION_S
 DECLARE_GL_FUNCTION_STUB_HEAD(void, PushName, GLuint name) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, PushName, name)
 DECLARE_GL_FUNCTION_STUB_HEAD(void, PopName) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, PopName)
 DECLARE_GL_FUNCTION_HEAD(void, ClampColor, GLenum target, GLenum clamp) DECLARE_GL_FUNCTION_END_NO_RETURN(void, ClampColor, target, clamp)
-DECLARE_GL_FUNCTION_STUB_HEAD(void, BeginConditionalRender, GLuint id, GLenum mode) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, BeginConditionalRender, id, mode)
-DECLARE_GL_FUNCTION_STUB_HEAD(void, EndConditionalRender, void) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, EndConditionalRender)
+DECLARE_GL_FUNCTION_HEAD(void, BeginConditionalRender, GLuint id, GLenum mode) DECLARE_GL_FUNCTION_END_NO_RETURN(void, BeginConditionalRender, id, mode)
+DECLARE_GL_FUNCTION_HEAD(void, EndConditionalRender) DECLARE_GL_FUNCTION_END_NO_RETURN(void, EndConditionalRender)
 DECLARE_GL_FUNCTION_HEAD(void, VertexAttribI1i, GLuint index, GLint x) DECLARE_GL_FUNCTION_END_NO_RETURN(void, VertexAttribI1i, index, x)
 DECLARE_GL_FUNCTION_HEAD(void, VertexAttribI2i, GLuint index, GLint x, GLint y) DECLARE_GL_FUNCTION_END_NO_RETURN(void, VertexAttribI2i, index, x, y)
 DECLARE_GL_FUNCTION_HEAD(void, VertexAttribI3i, GLuint index, GLint x, GLint y, GLint z) DECLARE_GL_FUNCTION_END_NO_RETURN(void, VertexAttribI3i, index, x, y, z)

MobileGL/MG_Impl/GLImpl/Framebuffer/GL_Framebuffer.cpp

@@ -2613,18 +2613,26 @@ namespace MobileGL::MG_Impl::GLImpl {
     }
 
     void ClearBufferfi_Backend(GLenum buffer, GLint drawbuffer, GLfloat depth, GLint stencil) {
+        // GL 4.6 core 10.9 makes ClearBuffer* conditional alongside the drawing commands.
+        if (MG_State::pGLContext->ConditionalRenderDiscardsCommands()) return;
         MG_Backend::gBackendFunctionsTable.GL.ClearBufferfi(buffer, drawbuffer, depth, stencil);
     }
 
     void ClearBufferfv_Backend(GLenum buffer, GLint drawbuffer, const GLfloat* value) {
+        // GL 4.6 core 10.9 makes ClearBuffer* conditional alongside the drawing commands.
+        if (MG_State::pGLContext->ConditionalRenderDiscardsCommands()) return;
         MG_Backend::gBackendFunctionsTable.GL.ClearBufferfv(buffer, drawbuffer, value);
     }
 
     void ClearBufferuiv_Backend(GLenum buffer, GLint drawbuffer, const GLuint* value) {
+        // GL 4.6 core 10.9 makes ClearBuffer* conditional alongside the drawing commands.
+        if (MG_State::pGLContext->ConditionalRenderDiscardsCommands()) return;
         MG_Backend::gBackendFunctionsTable.GL.ClearBufferuiv(buffer, drawbuffer, value);
     }
 
     void ClearBufferiv_Backend(GLenum buffer, GLint drawbuffer, const GLint* value) {
+        // GL 4.6 core 10.9 makes ClearBuffer* conditional alongside the drawing commands.
+        if (MG_State::pGLContext->ConditionalRenderDiscardsCommands()) return;
         MG_Backend::gBackendFunctionsTable.GL.ClearBufferiv(buffer, drawbuffer, value);
     }
 

MobileGL/MG_Impl/GLImpl/Query/GL_Query.cpp

@@ -565,6 +565,75 @@ namespace MobileGL::MG_Impl::GLImpl {
         queryObject->ended = true;
     }
 
+    void BeginConditionalRender(GLuint id, GLenum mode) {
+        // GL 4.6 core 10.9's eight modes. The _INVERTED half flips the sense of the predicate;
+        // the BY_REGION half only narrows WHERE an implementation is permitted to discard, so
+        // treating it as its whole-framebuffer sibling is what an implementation without region
+        // granularity does. The _NO_WAIT half is a permission to render rather than stall, not an
+        // obligation - see the resolve below.
+        Bool inverted = false;
+        switch (mode) {
+        case GL_QUERY_WAIT:
+        case GL_QUERY_NO_WAIT:
+        case GL_QUERY_BY_REGION_WAIT:
+        case GL_QUERY_BY_REGION_NO_WAIT:
+            inverted = false;
+            break;
+        case GL_QUERY_WAIT_INVERTED:
+        case GL_QUERY_NO_WAIT_INVERTED:
+        case GL_QUERY_BY_REGION_WAIT_INVERTED:
+        case GL_QUERY_BY_REGION_NO_WAIT_INVERTED:
+            inverted = true;
+            break;
+        default:
+            RecordQueryError(ErrorCode::InvalidEnum, __FUNCTION__, "mode is not a conditional render mode.");
+            return;
+        }
+
+        if (MG_State::pGLContext->IsConditionalRenderActive()) {
+            RecordQueryError(ErrorCode::InvalidOperation, __FUNCTION__, "Conditional rendering is already active.");
+            return;
+        }
+
+        {
+            const std::lock_guard<std::mutex> lock(g_queryObjectsMutex);
+            const auto* queryObject = FindQueryObjectLocked(id);
+            // A generated NAME is not yet a query object; it becomes one at its first use with a
+            // target (the same rule glIsQuery answers by).
+            if (!queryObject || (!queryObject->created && queryObject->target == 0)) {
+                RecordQueryError(ErrorCode::InvalidValue, __FUNCTION__, "id is not the name of a query object.");
+                return;
+            }
+            if (queryObject->active) {
+                RecordQueryError(ErrorCode::InvalidOperation, __FUNCTION__, "The query object is still active.");
+                return;
+            }
+            if (queryObject->target != GL_SAMPLES_PASSED && queryObject->target != GL_ANY_SAMPLES_PASSED &&
+                queryObject->target != GL_ANY_SAMPLES_PASSED_CONSERVATIVE) {
+                RecordQueryError(ErrorCode::InvalidOperation, __FUNCTION__,
+                                 "Conditional rendering requires an occlusion query object.");
+                return;
+            }
+        }
+
+        // Resolved ONCE, here, and by WAITING even for the _NO_WAIT modes: the spec lets those
+        // render instead of stalling, so always waiting is conforming and is the only choice that
+        // gives the whole block one deterministic verdict. Reading it per command instead would
+        // let a result that lands mid-block change the answer half way through.
+        Uint64 samplesPassed = 0;
+        if (!GetQueryObjectValue(id, GL_QUERY_RESULT, __FUNCTION__, samplesPassed)) return;
+        const Bool passed = samplesPassed != 0;
+        MG_State::pGLContext->BeginConditionalRender(id, mode, inverted ? passed : !passed);
+    }
+
+    void EndConditionalRender() {
+        if (!MG_State::pGLContext->IsConditionalRenderActive()) {
+            RecordQueryError(ErrorCode::InvalidOperation, __FUNCTION__, "Conditional rendering is not active.");
+            return;
+        }
+        MG_State::pGLContext->EndConditionalRender();
+    }
+
     void GetQueryiv(GLenum target, GLenum pname, GLint* params) {
         if (!params) {
             return;

MobileGL/MG_Impl/GLImpl/Query/GL_Query.h

@@ -29,6 +29,11 @@ namespace MobileGL::MG_Impl::GLImpl {
     void GetQueryBufferObjecti64v(GLuint id, GLuint buffer, GLenum pname, GLintptr offset);
     void GetQueryBufferObjectui64v(GLuint id, GLuint buffer, GLenum pname, GLintptr offset);
     void QueryCounter(GLuint id, GLenum target);
+    // Conditional rendering (GL 4.6 core 10.9). Implemented here rather than beside the drawing
+    // entry points because the predicate is a QUERY OBJECT's result, and the object registry -
+    // with the lock that guards it - lives in this file.
+    void BeginConditionalRender(GLuint id, GLenum mode);
+    void EndConditionalRender();
     // Destroys every still-registered query object exactly as DeleteQueries would.
     // GL requires queries to die with their context; called only from full library
     // teardown (DestroyImpl), where no context survives on any thread, so the

MobileGL/MG_State/GLState/Core.h

@@ -368,6 +368,31 @@ namespace MobileGL {
                     return m_transformFeedbackGeometryCaptureDraws;
                 }
 
+                // Conditional rendering (GL 4.6 core 10.9). `discard` is the verdict already
+                // resolved from the query object at glBeginConditionalRender - the predicate is
+                // read ONCE there, not per command, because GL specifies the block against the
+                // result available at Begin and re-reading it would let a query that is still
+                // being written change the answer mid-block.
+                void BeginConditionalRender(GLuint queryId, GLenum mode, Bool discard) {
+                    m_conditionalRenderActive = true;
+                    m_conditionalRenderQuery = queryId;
+                    m_conditionalRenderMode = mode;
+                    m_conditionalRenderDiscards = discard;
+                }
+                void EndConditionalRender() {
+                    m_conditionalRenderActive = false;
+                    m_conditionalRenderQuery = 0;
+                    m_conditionalRenderMode = GL_NONE;
+                    m_conditionalRenderDiscards = false;
+                }
+                Bool IsConditionalRenderActive() const { return m_conditionalRenderActive; }
+                GLuint GetConditionalRenderQuery() const { return m_conditionalRenderQuery; }
+                // Whether the commands GL 4.6 core 10.9 makes conditional are being discarded
+                // right now. False whenever no block is open, so a caller needs no second test.
+                Bool ConditionalRenderDiscardsCommands() const {
+                    return m_conditionalRenderActive && m_conditionalRenderDiscards;
+                }
+
                 // Transform feedback objects (ARB_transform_feedback2 / GL 4.0 core).
                 // The capture state above and the indexed GL_TRANSFORM_FEEDBACK_BUFFER
                 // binding points are object state, but the context keeps exactly one live
@@ -466,6 +491,13 @@ namespace MobileGL {
                 Uint64 m_transformFeedbackAccountedCaptureDraws = 0;
                 Uint64 m_transformFeedbackGeometryCaptureDraws = 0;
 
+                // Conditional rendering. Context state, not object state: GL 4.6 core 10.9 allows
+                // exactly one block open at a time and no object owns it.
+                Bool m_conditionalRenderActive = false;
+                Bool m_conditionalRenderDiscards = false;
+                GLuint m_conditionalRenderQuery = 0;
+                GLenum m_conditionalRenderMode = GL_NONE;
+
                 // Everything a transform feedback object owns while it is NOT the bound one.
                 struct TransformFeedbackObjectState {
                     struct SavedBufferBinding {

MobileGL/MG_Test/Query/QueryTest.cpp

@@ -140,6 +140,29 @@ namespace {
 
     void StubEndXfbPrimitivesQuery(MG_Backend::BackendQueryHandle) { ++g_stubXfbEndCount; }
 
+    // Stub backend occlusion queries. The host has no ES context, and BeginQuery refuses the
+    // occlusion targets outright when the backend advertises no hook - so a conditional-render
+    // test cannot get a legal predicate object without these. g_stubResultNs is the sample count
+    // the "driver" reports, which is the whole input to the predicate.
+    MG_Backend::BackendQueryHandle StubBeginOcclusionQuery() {
+        return reinterpret_cast<MG_Backend::BackendQueryHandle>(static_cast<uintptr_t>(0x54));
+    }
+
+    void StubEndOcclusionQuery(MG_Backend::BackendQueryHandle) {}
+
+    void InstallStubBackendOcclusionQueries() {
+        auto& backendGL = MG_Backend::gBackendFunctionsTable.GL;
+        backendGL.BeginOcclusionQuery = StubBeginOcclusionQuery;
+        backendGL.EndOcclusionQuery = StubEndOcclusionQuery;
+        backendGL.IsQueryResultAvailable = StubIsQueryResultAvailable;
+        backendGL.GetQueryResult64 = StubGetQueryResult64;
+        backendGL.DeleteBackendQuery = StubDeleteBackendQuery;
+        g_stubDeleteCount = 0;
+        g_stubResultAvailable = true;
+        g_stubResultObtainable = true;
+        g_stubResultNs = 0;
+    }
+
     void InstallStubBackendXfbQueries() {
         auto& backendGL = MG_Backend::gBackendFunctionsTable.GL;
         backendGL.BeginXfbPrimitivesQuery = StubBeginXfbPrimitivesQuery;
@@ -677,6 +700,108 @@ TEST_F(QueryTest, PrimitivesGeneratedKeepsTheBackendResultUnderTheCpuPreference)
 // unified truthy rule (set, non-empty, not "0", case-insensitive not "false").
 // Running the binary under MOBILEGL_DISABLE_TIMERQUERY=1 therefore exercises
 // the real end-to-end path rather than the struct field alone.
+// KHR-GL43.compute_shader.conditional-dispatching and the conditional_render family.
+// glBeginConditionalRender/glEndConditionalRender were bare stubs: every command inside a
+// conditional block executed whatever the query said, so the block that should have been
+// discarded ran and doubled the atomic counter the case reads back.
+TEST_F(QueryTest, ConditionalRenderResolvesItsPredicateFromTheOcclusionQuery) {
+    ScopedBackendFunctionsOverride backendGuard;
+    InstallStubBackendOcclusionQueries();
+
+    GLuint ids[2] = {0, 0};
+    MG_Impl::GLImpl::GenQueries(2, ids);
+    ASSERT_NE(ids[0], 0u);
+    ASSERT_NE(ids[1], 0u);
+
+    // One span that saw samples and one that saw none, which is exactly the pair the
+    // conformance case builds out of a passing and a failing depth test.
+    g_stubResultNs = 1;
+    MG_Impl::GLImpl::BeginQuery(GL_ANY_SAMPLES_PASSED, ids[0]);
+    MG_Impl::GLImpl::EndQuery(GL_ANY_SAMPLES_PASSED);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    GLuint passedResult = 0xFFFFFFFFu;
+    MG_Impl::GLImpl::GetQueryObjectuiv(ids[0], GL_QUERY_RESULT, &passedResult);
+    ASSERT_EQ(passedResult, 1u);
+
+    g_stubResultNs = 0;
+    MG_Impl::GLImpl::BeginQuery(GL_ANY_SAMPLES_PASSED, ids[1]);
+    MG_Impl::GLImpl::EndQuery(GL_ANY_SAMPLES_PASSED);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // A block on the query that passed executes.
+    MG_Impl::GLImpl::BeginConditionalRender(ids[0], GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    EXPECT_TRUE(MG_State::pGLContext->IsConditionalRenderActive());
+    EXPECT_FALSE(MG_State::pGLContext->ConditionalRenderDiscardsCommands());
+    MG_Impl::GLImpl::EndConditionalRender();
+    EXPECT_FALSE(MG_State::pGLContext->IsConditionalRenderActive());
+    EXPECT_FALSE(MG_State::pGLContext->ConditionalRenderDiscardsCommands());
+
+    // A block on the query that did not passes nothing through.
+    MG_Impl::GLImpl::BeginConditionalRender(ids[1], GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    EXPECT_TRUE(MG_State::pGLContext->ConditionalRenderDiscardsCommands());
+    MG_Impl::GLImpl::EndConditionalRender();
+
+    // ...and the _INVERTED modes swap both verdicts.
+    MG_Impl::GLImpl::BeginConditionalRender(ids[0], GL_QUERY_WAIT_INVERTED);
+    EXPECT_TRUE(MG_State::pGLContext->ConditionalRenderDiscardsCommands());
+    MG_Impl::GLImpl::EndConditionalRender();
+    MG_Impl::GLImpl::BeginConditionalRender(ids[1], GL_QUERY_BY_REGION_NO_WAIT_INVERTED);
+    EXPECT_FALSE(MG_State::pGLContext->ConditionalRenderDiscardsCommands());
+    MG_Impl::GLImpl::EndConditionalRender();
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::DeleteQueries(2, ids);
+}
+
+TEST_F(QueryTest, ConditionalRenderRejectsTheErrorsTheSpecNames) {
+    ScopedBackendFunctionsOverride backendGuard;
+    InstallStubBackendOcclusionQueries();
+
+    GLuint ids[2] = {0, 0};
+    MG_Impl::GLImpl::GenQueries(2, ids);
+    g_stubResultNs = 1;
+    MG_Impl::GLImpl::BeginQuery(GL_ANY_SAMPLES_PASSED, ids[0]);
+    MG_Impl::GLImpl::EndQuery(GL_ANY_SAMPLES_PASSED);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // GL 4.6 core 10.9, one rule at a time.
+    MG_Impl::GLImpl::BeginConditionalRender(ids[0], GL_TIME_ELAPSED);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_ENUM);
+    EXPECT_FALSE(MG_State::pGLContext->IsConditionalRenderActive());
+
+    // A generated NAME is not yet a query object.
+    MG_Impl::GLImpl::BeginConditionalRender(ids[1], GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_VALUE);
+    MG_Impl::GLImpl::BeginConditionalRender(0, GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_VALUE);
+
+    // A query that is not an occlusion query cannot drive one.
+    GLuint timerId = 0;
+    MG_Impl::GLImpl::GenQueries(1, &timerId);
+    MG_Impl::GLImpl::BeginQuery(GL_TIME_ELAPSED, timerId);
+    MG_Impl::GLImpl::EndQuery(GL_TIME_ELAPSED);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::BeginConditionalRender(timerId, GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_OPERATION);
+
+    // End without a block, and a nested Begin.
+    MG_Impl::GLImpl::EndConditionalRender();
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_OPERATION);
+    MG_Impl::GLImpl::BeginConditionalRender(ids[0], GL_QUERY_WAIT);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::BeginConditionalRender(ids[0], GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_OPERATION);
+    // The rejected nested Begin must not have disturbed the open block.
+    EXPECT_EQ(MG_State::pGLContext->GetConditionalRenderQuery(), ids[0]);
+    MG_Impl::GLImpl::EndConditionalRender();
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::DeleteQueries(2, ids);
+    MG_Impl::GLImpl::DeleteQueries(1, &timerId);
+}
+
 TEST_F(QueryTest, DisableTimerQueryFeatureMatchesEnvironment) {
     const char* raw = std::getenv("MOBILEGL_DISABLE_TIMERQUERY");
     Bool expected = false;