Set the stencil buffer zone

This only clears the area that update stencil buffer for a better
performance. The information that is to be updated utilizes
information located in the following node's siccor area.

Change-Id: I9a399667ec7ee0a1028e233c899ee49c98e4e622
Task-number: QTBUG-83108
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 33 insertions, 9 deletions

diff --git a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
index a74e82b1bd..131790b19a 100644
--- a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
@@ -2427,20 +2427,18 @@ ClipState::ClipType Renderer::updateStencilClip(const QSGClipNode *clip)
         // TODO: Check for multisampling and pixel grid alignment.
         bool isRectangleWithNoPerspective = clip->isRectangular()
                 && qFuzzyIsNull(m(3, 0)) && qFuzzyIsNull(m(3, 1));
-        bool noRotate = qFuzzyIsNull(m(0, 1)) && qFuzzyIsNull(m(1, 0));
-        bool isRotate90 = qFuzzyIsNull(m(0, 0)) && qFuzzyIsNull(m(1, 1));
-
-        if (isRectangleWithNoPerspective && (noRotate || isRotate90)) {
-            QRectF bbox = clip->clipRect();
+        auto noRotate = [] (const QMatrix4x4 &m) { return qFuzzyIsNull(m(0, 1)) && qFuzzyIsNull(m(1, 0)); };
+        auto isRotate90 = [] (const QMatrix4x4 &m) { return qFuzzyIsNull(m(0, 0)) && qFuzzyIsNull(m(1, 1)); };
+        auto scissorRect = [&] (const QRectF &bbox, const QMatrix4x4 &m) {
             qreal invW = 1 / m(3, 3);
             qreal fx1, fy1, fx2, fy2;
-            if (noRotate) {
+            if (noRotate(m)) {
                 fx1 = (bbox.left() * m(0, 0) + m(0, 3)) * invW;
                 fy1 = (bbox.bottom() * m(1, 1) + m(1, 3)) * invW;
                 fx2 = (bbox.right() * m(0, 0) + m(0, 3)) * invW;
                 fy2 = (bbox.top() * m(1, 1) + m(1, 3)) * invW;
             } else {
-                Q_ASSERT(isRotate90);
+                Q_ASSERT(isRotate90(m));
                 fx1 = (bbox.bottom() * m(0, 1) + m(0, 3)) * invW;
                 fy1 = (bbox.left() * m(1, 0) + m(1, 3)) * invW;
                 fx2 = (bbox.top() * m(0, 1) + m(0, 3)) * invW;
@@ -2459,12 +2457,18 @@ ClipState::ClipType Renderer::updateStencilClip(const QSGClipNode *clip)
             GLint ix2 = qRound((fx2 + 1) * deviceRect.width() * qreal(0.5));
             GLint iy2 = qRound((fy2 + 1) * deviceRect.height() * qreal(0.5));
 
+            return QRect(ix1, iy1, ix2 - ix1, iy2 - iy1);
+        };
+
+        if (isRectangleWithNoPerspective && (noRotate(m) || isRotate90(m))) {
+            auto rect = scissorRect(clip->clipRect(), m);
+
             if (!(clipType & ClipState::ScissorClip)) {
-                m_currentScissorRect = QRect(ix1, iy1, ix2 - ix1, iy2 - iy1);
+                m_currentScissorRect = rect;
                 glEnable(GL_SCISSOR_TEST);
                 clipType |= ClipState::ScissorClip;
             } else {
-                m_currentScissorRect &= QRect(ix1, iy1, ix2 - ix1, iy2 - iy1);
+                m_currentScissorRect &= rect;
             }
             glScissor(m_currentScissorRect.x(), m_currentScissorRect.y(),
                       m_currentScissorRect.width(), m_currentScissorRect.height());
@@ -2479,9 +2483,29 @@ ClipState::ClipType Renderer::updateStencilClip(const QSGClipNode *clip)
                     m_clipProgram.link();
                     m_clipMatrixId = m_clipProgram.uniformLocation("matrix");
                 }
+                const QSGClipNode *clipNext = clip->clipList();
+                QMatrix4x4 mNext = m_current_projection_matrix;
+                if (clipNext->matrix())
+                    mNext *= *clipNext->matrix();
+
+                auto rect = scissorRect(clipNext->clipRect(), mNext);
+
+                ClipState::ClipType clipTypeNext = clipType ;
+                clipTypeNext |= ClipState::StencilClip;
+                QRect m_next_scissor_rect = m_currentScissorRect;
+                if (!(clipTypeNext & ClipState::ScissorClip)) {
+                    m_next_scissor_rect = rect;
+                    glEnable(GL_SCISSOR_TEST);
+                } else {
+                    m_next_scissor_rect =
+                       m_currentScissorRect & rect;
+                }
+                glScissor(m_next_scissor_rect.x(), m_next_scissor_rect.y(),
+                          m_next_scissor_rect.width(), m_next_scissor_rect.height());
 
                 glClearStencil(0);
                 glClear(GL_STENCIL_BUFFER_BIT);
+                glDisable(GL_SCISSOR_TEST);
                 glEnable(GL_STENCIL_TEST);
                 glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
                 glDepthMask(GL_FALSE);