QOpenGLShader: report geom. and tess. on GLES 3.2+

Also fix up the docs.

To make everything more complicated, OpenGL ES 3.2 does not support
default tessellation levels. Therefore the related functions remain
OpenGL 4.0+ only.

[ChangeLog][QtGui] QOpenGLShader has been fixed to expose geometry and
tessellation evaluation/control shaders with OpenGL ES 3.2.

Task-number: QTBUG-66074
Change-Id: I2e4277912800d8302824e3fb74f61ec16f4b341d
Reviewed-by: Paolo Angelelli <paolo.angelelli@qt.io>
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 33 insertions, 44 deletions

diff --git a/src/gui/opengl/qopenglshaderprogram.cpp b/src/gui/opengl/qopenglshaderprogram.cpp
index 6d7aecac6f..c39177080d 100644
--- a/src/gui/opengl/qopenglshaderprogram.cpp
+++ b/src/gui/opengl/qopenglshaderprogram.cpp
@@ -39,7 +39,7 @@
 
 #include "qopenglshaderprogram.h"
 #include "qopenglprogrambinarycache_p.h"
-#include "qopenglfunctions.h"
+#include "qopenglextrafunctions.h"
 #include "private/qopenglcontext_p.h"
 #include <QtCore/private/qobject_p.h>
 #include <QtCore/qdebug.h>
@@ -170,13 +170,13 @@ QT_BEGIN_NAMESPACE
     \value Vertex Vertex shader written in the OpenGL Shading Language (GLSL).
     \value Fragment Fragment shader written in the OpenGL Shading Language (GLSL).
     \value Geometry Geometry shaders written in the OpenGL Shading Language (GLSL)
-           based on the OpenGL core feature (requires OpenGL >= 3.2).
+           (requires OpenGL >= 3.2 or OpenGL ES >= 3.2).
     \value TessellationControl Tessellation control shaders written in the OpenGL
-           shading language (GLSL), based on the core feature (requires OpenGL >= 4.0).
+           shading language (GLSL) (requires OpenGL >= 4.0 or OpenGL ES >= 3.2).
     \value TessellationEvaluation Tessellation evaluation shaders written in the OpenGL
-           shading language (GLSL), based on the core feature (requires OpenGL >= 4.0).
-    \value Compute Compute shaders written in the OpenGL shading language (GLSL),
-           based on the core feature (requires OpenGL >= 4.3).
+           shading language (GLSL) (requires OpenGL >= 4.0 or OpenGL ES >= 3.2).
+    \value Compute Compute shaders written in the OpenGL shading language (GLSL)
+           (requires OpenGL >= 4.3 or OpenGL ES >= 3.1).
 */
 
 Q_LOGGING_CATEGORY(DBG_SHADER_CACHE, "qt.opengl.diskcache")
@@ -223,26 +223,18 @@ static inline bool isFormatGLES(const QSurfaceFormat &f)
 
 static inline bool supportsGeometry(const QSurfaceFormat &f)
 {
-#ifndef QT_OPENGL_ES_2
-    if (!isFormatGLES(f))
-        return (f.version() >= qMakePair<int, int>(3, 2));
-    else
-        return false;
-#else
-    Q_UNUSED(f);
-    return false;
-#endif
+    return f.version() >= qMakePair(3, 2);
 }
 
 static inline bool supportsCompute(const QSurfaceFormat &f)
 {
 #ifndef QT_OPENGL_ES_2
     if (!isFormatGLES(f))
-        return (f.version() >= qMakePair<int, int>(4, 3));
+        return f.version() >= qMakePair(4, 3);
     else
-        return (f.version() >= qMakePair<int, int>(3, 1));
+        return f.version() >= qMakePair(3, 1);
 #else
-    return (f.version() >= qMakePair<int, int>(3, 1));
+    return f.version() >= qMakePair(3, 1);
 #endif
 }
 
@@ -250,12 +242,11 @@ static inline bool supportsTessellation(const QSurfaceFormat &f)
 {
 #ifndef QT_OPENGL_ES_2
     if (!isFormatGLES(f))
-        return (f.version() >= qMakePair<int, int>(4, 0));
+        return f.version() >= qMakePair(4, 0);
     else
-        return false;
+        return f.version() >= qMakePair(3, 2);
 #else
-    Q_UNUSED(f);
-    return false;
+    return f.version() >= qMakePair(3, 2);
 #endif
 }
 
@@ -267,7 +258,7 @@ public:
         : shaderGuard(0)
         , shaderType(type)
         , compiled(false)
-        , glfuncs(new QOpenGLFunctions(ctx))
+        , glfuncs(new QOpenGLExtraFunctions(ctx))
         , supportsGeometryShaders(false)
         , supportsTessellationShaders(false)
         , supportsComputeShaders(false)
@@ -286,7 +277,7 @@ public:
     bool compiled;
     QString log;
 
-    QOpenGLFunctions *glfuncs;
+    QOpenGLExtraFunctions *glfuncs;
 
     // Support for geometry shaders
     bool supportsGeometryShaders;
@@ -802,7 +793,7 @@ public:
         , linked(false)
         , inited(false)
         , removingShaders(false)
-        , glfuncs(new QOpenGLFunctions)
+        , glfuncs(new QOpenGLExtraFunctions)
 #ifndef QT_OPENGL_ES_2
         , tessellationFuncs(0)
 #endif
@@ -820,10 +811,9 @@ public:
     QList<QOpenGLShader *> shaders;
     QList<QOpenGLShader *> anonShaders;
 
-    QOpenGLFunctions *glfuncs;
-
+    QOpenGLExtraFunctions *glfuncs;
 #ifndef QT_OPENGL_ES_2
-    // Tessellation shader support
+    // for tessellation features not in GLES 3.2
     QOpenGLFunctions_4_0_Core *tessellationFuncs;
 #endif
 
@@ -913,10 +903,7 @@ bool QOpenGLShaderProgram::init()
     d->glfuncs->initializeOpenGLFunctions();
 
 #ifndef QT_OPENGL_ES_2
-    // Resolve OpenGL 4 functions for tessellation shader support
-    QSurfaceFormat format = context->format();
-    if (!context->isOpenGLES()
-        && format.version() >= qMakePair<int, int>(4, 0)) {
+    if (!context->isOpenGLES() && context->format().version() >= qMakePair(4, 0)) {
         d->tessellationFuncs = context->versionFunctions<QOpenGLFunctions_4_0_Core>();
         d->tessellationFuncs->initializeOpenGLFunctions();
     }
@@ -3508,13 +3495,8 @@ int QOpenGLShaderProgram::maxGeometryOutputVertices() const
 */
 void QOpenGLShaderProgram::setPatchVertexCount(int count)
 {
-#ifndef QT_OPENGL_ES_2
     Q_D(QOpenGLShaderProgram);
-    if (d->tessellationFuncs)
-        d->tessellationFuncs->glPatchParameteri(GL_PATCH_VERTICES, count);
-#else
-    Q_UNUSED(count);
-#endif
+    d->glfuncs->glPatchParameteri(GL_PATCH_VERTICES, count);
 }
 
 /*!
@@ -3527,15 +3509,10 @@ void QOpenGLShaderProgram::setPatchVertexCount(int count)
 */
 int QOpenGLShaderProgram::patchVertexCount() const
 {
-#ifndef QT_OPENGL_ES_2
     int patchVertices = 0;
     Q_D(const QOpenGLShaderProgram);
-    if (d->tessellationFuncs)
-        d->tessellationFuncs->glGetIntegerv(GL_PATCH_VERTICES, &patchVertices);
+    d->glfuncs->glGetIntegerv(GL_PATCH_VERTICES, &patchVertices);
     return patchVertices;
-#else
-    return 0;
-#endif
 }
 
 /*!
@@ -3553,6 +3530,9 @@ int QOpenGLShaderProgram::patchVertexCount() const
     function when needed, as QOpenGLShaderProgram will not apply this for
     you. This is purely a convenience function.
 
+    \note This function is only available with OpenGL >= 4.0 and is not supported
+    with OpenGL ES 3.2.
+
     \sa defaultOuterTessellationLevels(), setDefaultInnerTessellationLevels()
 */
 void QOpenGLShaderProgram::setDefaultOuterTessellationLevels(const QVector<float> &levels)
@@ -3590,6 +3570,9 @@ void QOpenGLShaderProgram::setDefaultOuterTessellationLevels(const QVector<float
     \note This returns the global OpenGL state value. It is not specific to
     this QOpenGLShaderProgram instance.
 
+    \note This function is only supported with OpenGL >= 4.0 and will not
+    return valid results with OpenGL ES 3.2.
+
     \sa setDefaultOuterTessellationLevels(), defaultInnerTessellationLevels()
 */
 QVector<float> QOpenGLShaderProgram::defaultOuterTessellationLevels() const
@@ -3620,6 +3603,9 @@ QVector<float> QOpenGLShaderProgram::defaultOuterTessellationLevels() const
     function when needed, as QOpenGLShaderProgram will not apply this for
     you. This is purely a convenience function.
 
+    \note This function is only available with OpenGL >= 4.0 and is not supported
+    with OpenGL ES 3.2.
+
     \sa defaultInnerTessellationLevels(), setDefaultOuterTessellationLevels()
 */
 void QOpenGLShaderProgram::setDefaultInnerTessellationLevels(const QVector<float> &levels)
@@ -3657,6 +3643,9 @@ void QOpenGLShaderProgram::setDefaultInnerTessellationLevels(const QVector<float
     \note This returns the global OpenGL state value. It is not specific to
     this QOpenGLShaderProgram instance.
 
+    \note This function is only supported with OpenGL >= 4.0 and will not
+    return valid results with OpenGL ES 3.2.
+
     \sa setDefaultInnerTessellationLevels(), defaultOuterTessellationLevels()
 */
 QVector<float> QOpenGLShaderProgram::defaultInnerTessellationLevels() const