From 87088296d83993199f21b41b08d19882ef60c259 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Wed, 3 Mar 2021 14:46:14 +0100
Subject: [PATCH] GL: this TimeQuery test was just dumb.

Ah the good old times where my brain was not overflowing with
unnecessarily deep knowledge about how GPUs (and OpenGL drivers in
particular) work. Nope, switching a blend state and calling glFinish()
won't generate any GPU work, that will be all deferred until there's
something to be actually drawn, cleared or copied.
---
 src/Magnum/GL/Test/TimeQueryGLTest.cpp | 60 ++++++++++++++++++++------
 1 file changed, 47 insertions(+), 13 deletions(-)

diff --git a/src/Magnum/GL/Test/TimeQueryGLTest.cpp b/src/Magnum/GL/Test/TimeQueryGLTest.cpp
index e50768b4c..9f1e48569 100644
--- a/src/Magnum/GL/Test/TimeQueryGLTest.cpp
+++ b/src/Magnum/GL/Test/TimeQueryGLTest.cpp
@@ -27,7 +27,10 @@
 
 #include "Magnum/GL/Context.h"
 #include "Magnum/GL/Extensions.h"
+#include "Magnum/GL/Framebuffer.h"
 #include "Magnum/GL/OpenGLTester.h"
+#include "Magnum/GL/Renderbuffer.h"
+#include "Magnum/GL/RenderbufferFormat.h"
 #include "Magnum/GL/TimeQuery.h"
 
 namespace Magnum { namespace GL { namespace Test { namespace {
@@ -105,22 +108,37 @@ void TimeQueryGLTest::queryTime() {
         CORRADE_SKIP(Extensions::EXT::disjoint_timer_query::string() + std::string(" is not available"));
     #endif
 
+    Renderbuffer renderbuffer;
+    renderbuffer.setStorage(
+        #ifndef MAGNUM_TARGET_GLES2
+        RenderbufferFormat::RGBA8,
+        #else
+        RenderbufferFormat::RGBA4,
+        #endif
+        Vector2i(32));
+
+    Framebuffer framebuffer({{}, Vector2i{256, 256}});
+    framebuffer.attachRenderbuffer(Framebuffer::ColorAttachment(0), renderbuffer);
+
+    /* A query with nothing inside should be almost zero */
     TimeQuery q1{TimeQuery::Target::TimeElapsed};
     q1.begin();
     q1.end();
-    const auto result1 = q1.result<UnsignedInt>();
-
+    const auto result1 = q1.result<UnsignedLong>();
     MAGNUM_VERIFY_NO_GL_ERROR();
+    Debug{} << "Doing nothing took" << result1/1.0e6f << "ms";
+    CORRADE_COMPARE_AS(result1, 0, TestSuite::Compare::GreaterOrEqual);
 
+    /* A query with a clear inside should be nonzero and larger than nothing */
     TimeQuery q2{TimeQuery::Target::TimeElapsed};
     q2.begin();
-    Renderer::enable(Renderer::Feature::Blending);
-    Renderer::finish();
+    framebuffer.clear(FramebufferClear::Color);
     q2.end();
-    const auto result2 = q2.result<UnsignedInt>();
-
+    const auto result2 = q2.result<UnsignedLong>();
     MAGNUM_VERIFY_NO_GL_ERROR();
-    CORRADE_COMPARE_AS(result2, result1, TestSuite::Compare::GreaterOrEqual);
+    Debug{} << "Clear took" << result2/1.0e6f << "ms";
+    CORRADE_VERIFY(result2);
+    CORRADE_COMPARE_AS(result2, result1, TestSuite::Compare::Greater);
 }
 
 void TimeQueryGLTest::queryTimestamp() {
@@ -135,6 +153,18 @@ void TimeQueryGLTest::queryTimestamp() {
         CORRADE_SKIP(Extensions::EXT::disjoint_timer_query::string() + std::string(" is not available"));
     #endif
 
+    Renderbuffer renderbuffer;
+    renderbuffer.setStorage(
+        #ifndef MAGNUM_TARGET_GLES2
+        RenderbufferFormat::RGBA8,
+        #else
+        RenderbufferFormat::RGBA4,
+        #endif
+        Vector2i(32));
+
+    Framebuffer framebuffer({{}, Vector2i{256, 256}});
+    framebuffer.attachRenderbuffer(Framebuffer::ColorAttachment(0), renderbuffer);
+
     TimeQuery q1{TimeQuery::Target::Timestamp},
         q2{TimeQuery::Target::Timestamp},
         q{TimeQuery::Target::TimeElapsed};
@@ -142,19 +172,23 @@ void TimeQueryGLTest::queryTimestamp() {
     q1.timestamp();
 
     q.begin();
-    Renderer::enable(Renderer::Feature::Blending);
-    Renderer::finish();
+    framebuffer.clear(FramebufferClear::Color);
     q.end();
 
     q2.timestamp();
 
-    const auto result = q.result<UnsignedInt>();
+    const auto result = q.result<UnsignedLong>();
     const auto result1 = q1.result<UnsignedLong>();
     const auto result2 = q2.result<UnsignedLong>();
-
     MAGNUM_VERIFY_NO_GL_ERROR();
-    CORRADE_COMPARE_AS(result2, result1, TestSuite::Compare::GreaterOrEqual);
-    CORRADE_COMPARE_AS(result2 - result1, result, TestSuite::Compare::GreaterOrEqual);
+
+    Debug{} << "Clear took" << result/1.0e6f << "ms, timestamp difference is"
+        << (result2 - result1)/1.0e6f << "ms";
+
+    /* The timestamps should be monotonically increasing and the difference
+       slightly larger than the elapsed time because these are outside of it */
+    CORRADE_COMPARE_AS(result2, result1, TestSuite::Compare::Greater);
+    CORRADE_COMPARE_AS(result2 - result1, result, TestSuite::Compare::Greater);
 }
 
 }}}}