Add support for OpenGL 3.2+ core profile contexts in QPainter

This change allows painting via QPainter onto a QOpenGLWindow, QOpenGLWidget
or QOpenGLFramebufferObject when an core profile context is in use. This is
important on macOS in particular, where compatibility profiles are not
available, and so the only way to use modern OpenGL is via a core profile
context.

Added core profile compatible shaders with moder GLSL keywords.

The paint engine binds a VAO and two VBOs from now on, whenever VAOs are
supported. Note that this changes behavior also for OpenGL 2.x context that
have VAO support via extensions.

The Lancelot test suite gains support for core profile contexts. This can
be triggered via -coreglbuffer in place of -glbuffer when manually inspecting
via 'lance', while tst_lancelot will automatically run core context-based tests
whenever supported.

Task-number: QTBUG-33535
Change-Id: I6323a7ea2aaa9e111651ebbffd3e40259c8e7a9c
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

1 files changed, 79 insertions, 23 deletions

diff --git a/src/gui/opengl/qopenglengineshadermanager.cpp b/src/gui/opengl/qopenglengineshadermanager.cpp
index c7e457b364..dd9e8e9d1e 100644
--- a/src/gui/opengl/qopenglengineshadermanager.cpp
+++ b/src/gui/opengl/qopenglengineshadermanager.cpp
@@ -126,11 +126,65 @@ QOpenGLEngineSharedShaders::QOpenGLEngineSharedShaders(QOpenGLContext* context)
     around without having to change the order of the glsl strings. It is hoped this will
     make future hard-to-find runtime bugs more obvious and generally give more solid code.
 */
-    static bool snippetsPopulated = false;
-    if (!snippetsPopulated) {
 
-        const char** code = qShaderSnippets; // shortcut
+    // Check if the user has requested an OpenGL 3.2 Core Profile or higher
+    // and if so use GLSL 1.50 core shaders instead of legacy ones.
+    const QSurfaceFormat &fmt = context->format();
+    const bool isCoreProfile = fmt.profile() == QSurfaceFormat::CoreProfile && fmt.version() >= qMakePair(3,2);
+
+    const char** code = qShaderSnippets; // shortcut
+
+    if (isCoreProfile) {
+        code[MainVertexShader] = qopenglslMainVertexShader_core;
+        code[MainWithTexCoordsVertexShader] = qopenglslMainWithTexCoordsVertexShader_core;
+        code[MainWithTexCoordsAndOpacityVertexShader] = qopenglslMainWithTexCoordsAndOpacityVertexShader_core;
+
+        code[UntransformedPositionVertexShader] = qopenglslUntransformedPositionVertexShader_core;
+        code[PositionOnlyVertexShader] = qopenglslPositionOnlyVertexShader_core;
+        code[ComplexGeometryPositionOnlyVertexShader] = qopenglslComplexGeometryPositionOnlyVertexShader_core;
+        code[PositionWithPatternBrushVertexShader] = qopenglslPositionWithPatternBrushVertexShader_core;
+        code[PositionWithLinearGradientBrushVertexShader] = qopenglslPositionWithLinearGradientBrushVertexShader_core;
+        code[PositionWithConicalGradientBrushVertexShader] = qopenglslPositionWithConicalGradientBrushVertexShader_core;
+        code[PositionWithRadialGradientBrushVertexShader] = qopenglslPositionWithRadialGradientBrushVertexShader_core;
+        code[PositionWithTextureBrushVertexShader] = qopenglslPositionWithTextureBrushVertexShader_core;
+        code[AffinePositionWithPatternBrushVertexShader] = qopenglslAffinePositionWithPatternBrushVertexShader_core;
+        code[AffinePositionWithLinearGradientBrushVertexShader] = qopenglslAffinePositionWithLinearGradientBrushVertexShader_core;
+        code[AffinePositionWithConicalGradientBrushVertexShader] = qopenglslAffinePositionWithConicalGradientBrushVertexShader_core;
+        code[AffinePositionWithRadialGradientBrushVertexShader] = qopenglslAffinePositionWithRadialGradientBrushVertexShader_core;
+        code[AffinePositionWithTextureBrushVertexShader] = qopenglslAffinePositionWithTextureBrushVertexShader_core;
+
+        code[MainFragmentShader_CMO] = qopenglslMainFragmentShader_CMO_core;
+        code[MainFragmentShader_CM] = qopenglslMainFragmentShader_CM_core;
+        code[MainFragmentShader_MO] = qopenglslMainFragmentShader_MO_core;
+        code[MainFragmentShader_M] = qopenglslMainFragmentShader_M_core;
+        code[MainFragmentShader_CO] = qopenglslMainFragmentShader_CO_core;
+        code[MainFragmentShader_C] = qopenglslMainFragmentShader_C_core;
+        code[MainFragmentShader_O] = qopenglslMainFragmentShader_O_core;
+        code[MainFragmentShader] = qopenglslMainFragmentShader_core;
+        code[MainFragmentShader_ImageArrays] = qopenglslMainFragmentShader_ImageArrays_core;
+
+        code[ImageSrcFragmentShader] = qopenglslImageSrcFragmentShader_core;
+        code[ImageSrcWithPatternFragmentShader] = qopenglslImageSrcWithPatternFragmentShader_core;
+        code[NonPremultipliedImageSrcFragmentShader] = qopenglslNonPremultipliedImageSrcFragmentShader_core;
+        code[GrayscaleImageSrcFragmentShader] = qopenglslGrayscaleImageSrcFragmentShader_core;
+        code[AlphaImageSrcFragmentShader] = qopenglslAlphaImageSrcFragmentShader_core;
+        code[CustomImageSrcFragmentShader] = qopenglslCustomSrcFragmentShader_core; // Calls "customShader", which must be appended
+        code[SolidBrushSrcFragmentShader] = qopenglslSolidBrushSrcFragmentShader_core;
+
+        code[TextureBrushSrcFragmentShader] = qopenglslTextureBrushSrcFragmentShader_desktop_core;
+        code[TextureBrushSrcWithPatternFragmentShader] = qopenglslTextureBrushSrcWithPatternFragmentShader_core;
+        code[PatternBrushSrcFragmentShader] = qopenglslPatternBrushSrcFragmentShader_core;
+        code[LinearGradientBrushSrcFragmentShader] = qopenglslLinearGradientBrushSrcFragmentShader_core;
+        code[RadialGradientBrushSrcFragmentShader] = qopenglslRadialGradientBrushSrcFragmentShader_core;
+        code[ConicalGradientBrushSrcFragmentShader] = qopenglslConicalGradientBrushSrcFragmentShader_core;
+        code[ShockingPinkSrcFragmentShader] = qopenglslShockingPinkSrcFragmentShader_core;
 
+        code[NoMaskFragmentShader] = "";
+        code[MaskFragmentShader] = qopenglslMaskFragmentShader_core;
+        code[RgbMaskFragmentShaderPass1] = qopenglslRgbMaskFragmentShaderPass1_core;
+        code[RgbMaskFragmentShaderPass2] = qopenglslRgbMaskFragmentShaderPass2_core;
+        code[RgbMaskWithGammaFragmentShader] = ""; //###
+    } else {
         code[MainVertexShader] = qopenglslMainVertexShader;
         code[MainWithTexCoordsVertexShader] = qopenglslMainWithTexCoordsVertexShader;
         code[MainWithTexCoordsAndOpacityVertexShader] = qopenglslMainWithTexCoordsAndOpacityVertexShader;
@@ -182,31 +236,33 @@ QOpenGLEngineSharedShaders::QOpenGLEngineSharedShaders(QOpenGLContext* context)
         code[RgbMaskFragmentShaderPass1] = qopenglslRgbMaskFragmentShaderPass1;
         code[RgbMaskFragmentShaderPass2] = qopenglslRgbMaskFragmentShaderPass2;
         code[RgbMaskWithGammaFragmentShader] = ""; //###
+    }
 
-        code[NoCompositionModeFragmentShader] = "";
-        code[MultiplyCompositionModeFragmentShader] = ""; //###
-        code[ScreenCompositionModeFragmentShader] = ""; //###
-        code[OverlayCompositionModeFragmentShader] = ""; //###
-        code[DarkenCompositionModeFragmentShader] = ""; //###
-        code[LightenCompositionModeFragmentShader] = ""; //###
-        code[ColorDodgeCompositionModeFragmentShader] = ""; //###
-        code[ColorBurnCompositionModeFragmentShader] = ""; //###
-        code[HardLightCompositionModeFragmentShader] = ""; //###
-        code[SoftLightCompositionModeFragmentShader] = ""; //###
-        code[DifferenceCompositionModeFragmentShader] = ""; //###
-        code[ExclusionCompositionModeFragmentShader] = ""; //###
+    // These shaders are not implemented yet and therefore are the same
+    // for all profiles. Implementations should make a version for both
+    // profiles and put the appropriate lines in the if-statement above.
+    code[NoCompositionModeFragmentShader] = "";
+    code[MultiplyCompositionModeFragmentShader] = ""; //###
+    code[ScreenCompositionModeFragmentShader] = ""; //###
+    code[OverlayCompositionModeFragmentShader] = ""; //###
+    code[DarkenCompositionModeFragmentShader] = ""; //###
+    code[LightenCompositionModeFragmentShader] = ""; //###
+    code[ColorDodgeCompositionModeFragmentShader] = ""; //###
+    code[ColorBurnCompositionModeFragmentShader] = ""; //###
+    code[HardLightCompositionModeFragmentShader] = ""; //###
+    code[SoftLightCompositionModeFragmentShader] = ""; //###
+    code[DifferenceCompositionModeFragmentShader] = ""; //###
+    code[ExclusionCompositionModeFragmentShader] = ""; //###
 
 #if defined(QT_DEBUG)
-        // Check that all the elements have been filled:
-        for (int i = 0; i < TotalSnippetCount; ++i) {
-            if (Q_UNLIKELY(!qShaderSnippets[i])) {
-                qFatal("Shader snippet for %s (#%d) is missing!",
-                       snippetNameStr(SnippetName(i)).constData(), i);
-            }
+    // Check that all the elements have been filled:
+    for (int i = 0; i < TotalSnippetCount; ++i) {
+        if (Q_UNLIKELY(!qShaderSnippets[i])) {
+            qFatal("Shader snippet for %s (#%d) is missing!",
+                   snippetNameStr(SnippetName(i)).constData(), i);
         }
-#endif
-        snippetsPopulated = true;
     }
+#endif
 
     QByteArray vertexSource;
     QByteArray fragSource;