sg: Fix some material-related multiview issues

Every time type is compared and compare() is called, viewCount() must
also be compared.

More importantly, the correct view count (handled via internal flags
for SC/BC) has to be pushed to the QSGMaterial always, before checking
for an existing QSGMaterialShader - otherwise if material #2 has a hit
for a shader from material #1, material #2 will never have the view
count pushed so it continues to report viewCount() == 1, which
has...interesting consequences. Avoid this.

Change-Id: I0808cc57f53a8dab891d1b36b41790f58c978ef4
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

Author: alpqr

src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp

@@ -213,14 +213,15 @@ ShaderManager::Shader *ShaderManager::prepareMaterial(QSGMaterial *material,
                                                       QSGRendererInterface::RenderMode renderMode,
                                                       int multiViewCount)
 {
+    qsg_setMultiViewFlagsOnMaterial(material, multiViewCount);
+
     QSGMaterialType *type = material->type();
     ShaderKey key = { type, renderMode, multiViewCount };
     Shader *shader = rewrittenShaders.value(key, nullptr);
     if (shader)
         return shader;
 
     shader = new Shader;
-    qsg_setMultiViewFlagsOnMaterial(material, multiViewCount);
     QSGMaterialShader *s = static_cast<QSGMaterialShader *>(material->createShader(renderMode));
     context->initializeRhiShader(s, QShader::BatchableVertexShader);
     shader->materialShader = s;
@@ -242,14 +243,15 @@ ShaderManager::Shader *ShaderManager::prepareMaterialNoRewrite(QSGMaterial *mate
                                                                QSGRendererInterface::RenderMode renderMode,
                                                                int multiViewCount)
 {
+    qsg_setMultiViewFlagsOnMaterial(material, multiViewCount);
+
     QSGMaterialType *type = material->type();
     ShaderKey key = { type, renderMode, multiViewCount };
     Shader *shader = stockShaders.value(key, nullptr);
     if (shader)
         return shader;
 
     shader = new Shader;
-    qsg_setMultiViewFlagsOnMaterial(material, multiViewCount);
     QSGMaterialShader *s = static_cast<QSGMaterialShader *>(material->createShader(renderMode));
     context->initializeRhiShader(s, QShader::StandardShader);
     shader->materialShader = s;
@@ -705,7 +707,7 @@ BatchCompatibility Batch::isMaterialCompatible(Element *e) const
 
     QSGMaterial *m = e->node->activeMaterial();
     QSGMaterial *nm = n->node->activeMaterial();
-    return (nm->type() == m->type() && nm->compare(m) == 0)
+    return (nm->type() == m->type() && nm->viewCount() == m->viewCount() && nm->compare(m) == 0)
             ? BatchIsCompatible
             : BatchBreaksOnCompare;
 }
@@ -1739,6 +1741,7 @@ void Renderer::prepareOpaqueBatches()
                     && gni->geometry()->attributes() == gnj->geometry()->attributes()
                     && gni->inheritedOpacity() == gnj->inheritedOpacity()
                     && gni->activeMaterial()->type() == gnj->activeMaterial()->type()
+                    && gni->activeMaterial()->viewCount() == gnj->activeMaterial()->viewCount()
                     && gni->activeMaterial()->compare(gnj->activeMaterial()) == 0) {
                 ej->batch = batch;
                 next->nextInBatch = ej;
@@ -1850,6 +1853,7 @@ void Renderer::prepareAlphaBatches()
                     && gni->geometry()->attributes() == gnj->geometry()->attributes()
                     && gni->inheritedOpacity() == gnj->inheritedOpacity()
                     && gni->activeMaterial()->type() == gnj->activeMaterial()->type()
+                    && gni->activeMaterial()->viewCount() == gnj->activeMaterial()->viewCount()
                     && gni->activeMaterial()->compare(gnj->activeMaterial()) == 0) {
                 if (!overlapBounds.intersects(ej->bounds) || !checkOverlap(i+1, j - 1, ej->bounds)) {
                     ej->batch = batch;