Fix stencil clips with core profile contexts

Client-side pointers are not supported. Start using a VBO instead.

Task-number: QTBUG-57768
Change-Id: Ia7ac9b0838d837b02e8bf99fcd22f0373cb357c9
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

1 files changed, 22 insertions, 1 deletions

diff --git a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
index 6db96f369c..4893c175a3 100644
--- a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
@@ -2022,6 +2022,8 @@ Renderer::ClipType Renderer::updateStencilClip(const QSGClipNode *clip)
     }
 
     ClipType clipType = NoClip;
+    GLuint vbo = 0;
+    int vboSize = 0;
 
     glDisable(GL_SCISSOR_TEST);
 
@@ -2106,7 +2108,21 @@ Renderer::ClipType Renderer::updateStencilClip(const QSGClipNode *clip)
             const QSGGeometry *g = clip->geometry();
             Q_ASSERT(g->attributeCount() > 0);
             const QSGGeometry::Attribute *a = g->attributes();
-            glVertexAttribPointer(0, a->tupleSize, a->type, GL_FALSE, g->sizeOfVertex(), g->vertexData());
+
+            if (!vbo)
+                glGenBuffers(1, &vbo);
+
+            glBindBuffer(GL_ARRAY_BUFFER, vbo);
+
+            const int vertexByteSize = g->sizeOfVertex() * g->vertexCount();
+            if (vboSize < vertexByteSize) {
+                vboSize = vertexByteSize;
+                glBufferData(GL_ARRAY_BUFFER, vertexByteSize, g->vertexData(), GL_STATIC_DRAW);
+            } else {
+                glBufferSubData(GL_ARRAY_BUFFER, 0, vertexByteSize, g->vertexData());
+            }
+
+            glVertexAttribPointer(0, a->tupleSize, a->type, GL_FALSE, g->sizeOfVertex(), 0);
 
             m_clipProgram.setUniformValue(m_clipMatrixId, m);
             if (g->indexCount()) {
@@ -2115,12 +2131,17 @@ Renderer::ClipType Renderer::updateStencilClip(const QSGClipNode *clip)
                 glDrawArrays(g->drawingMode(), 0, g->vertexCount());
             }
 
+            glBindBuffer(GL_ARRAY_BUFFER, 0);
+
             ++m_currentStencilValue;
         }
 
         clip = clip->clipList();
     }
 
+    if (vbo)
+        glDeleteBuffers(1, &vbo);
+
     if (clipType & StencilClip) {
         m_clipProgram.disableAttributeArray(0);
         glStencilFunc(GL_EQUAL, m_currentStencilValue, 0xff); // stencil test, ref, test mask