Renderer: glDrawBuffers using QRenderTargetSelector drawBuffer

Change-Id: I760401c7749ca97801e2254cda6b306b1748e10d
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

6 files changed, 49 insertions, 7 deletions

diff --git a/src/render/backend/attachmentpack.cpp b/src/render/backend/attachmentpack.cpp
index 03bd723e3..95bdb3c0c 100644
--- a/src/render/backend/attachmentpack.cpp
+++ b/src/render/backend/attachmentpack.cpp
@@ -56,6 +56,16 @@ QVector<Attachment> AttachmentPack::attachments() const
     return m_attachments;
 }
 
+QList<QRenderAttachment::RenderAttachmentType> AttachmentPack::drawBuffers() const
+{
+    return m_drawBuffers;
+}
+
+void AttachmentPack::setDrawBuffers(const QList<QRenderAttachment::RenderAttachmentType> &drawBuffers)
+{
+    m_drawBuffers = drawBuffers;
+}
+
 Attachment::Attachment()
     : m_mipLevel(0)
     , m_layer(0)
diff --git a/src/render/backend/attachmentpack_p.h b/src/render/backend/attachmentpack_p.h
index c2fcb34e4..74c5d6430 100644
--- a/src/render/backend/attachmentpack_p.h
+++ b/src/render/backend/attachmentpack_p.h
@@ -64,9 +64,13 @@ public:
 
     void addAttachment(const Attachment &attachment);
     QVector<Attachment> attachments() const;
+    QList<QRenderAttachment::RenderAttachmentType> drawBuffers() const;
+
+    void setDrawBuffers(const QList<QRenderAttachment::RenderAttachmentType> &drawBuffers);
 
 private:
     QVector<Attachment> m_attachments;
+    QList<QRenderAttachment::RenderAttachmentType> m_drawBuffers;
 };
 
 } // Render
diff --git a/src/render/backend/jobs/renderviewjobutils.cpp b/src/render/backend/jobs/renderviewjobutils.cpp
index 22725eb06..d16d124a9 100644
--- a/src/render/backend/jobs/renderviewjobutils.cpp
+++ b/src/render/backend/jobs/renderviewjobutils.cpp
@@ -112,7 +112,8 @@ void setRenderViewConfigFromFrameGraphLeafNode(RenderView *rv, const FrameGraphN
 
             case FrameGraphNode::RenderTarget: {
                 // Can be set once and we take render target nearest to the leaf node
-                QNodeId renderTargetUid = static_cast<const RenderTargetSelector *>(node)->renderTargetUuid();
+                const RenderTargetSelector *targetSelector = static_cast<const RenderTargetSelector *>(node);
+                QNodeId renderTargetUid = targetSelector->renderTargetUuid();
                 HTarget renderTargetHandle = renderer->renderTargetManager()->lookupHandle(renderTargetUid);
                 if (rv->renderTargetHandle().isNull()) {
                     rv->setRenderTargetHandle(renderTargetHandle);
@@ -120,11 +121,17 @@ void setRenderViewConfigFromFrameGraphLeafNode(RenderView *rv, const FrameGraphN
                     RenderTarget *renderTarget = renderer->renderTargetManager()->data(renderTargetHandle);
                     if (renderTarget) {
                         // Add renderTarget Handle and build renderCommand AttachmentPack
+
+                        // Copy draw buffers list
+                        rv->setDrawBuffers(targetSelector->drawBuffers());
+
+                        // Copy attachments
                         Q_FOREACH (const QNodeId &attachmentId, renderTarget->renderAttachments()) {
                             RenderAttachment *attachment = renderer->attachmentManager()->lookupResource(attachmentId);
                             if (attachment)
                                 rv->addRenderAttachment(attachment->attachment());
                         }
+
                     }
                 }
                 break;
diff --git a/src/render/backend/qgraphicscontext.cpp b/src/render/backend/qgraphicscontext.cpp
index 166893f8c..e42bcbfac 100644
--- a/src/render/backend/qgraphicscontext.cpp
+++ b/src/render/backend/qgraphicscontext.cpp
@@ -328,13 +328,14 @@ void QGraphicsContext::activateRenderTarget(RenderTarget *renderTarget, const At
     }
     m_activeFBO = fboId;
     m_glHelper->bindFrameBufferObject(m_activeFBO);
+    // Set active drawBuffers
+    activateDrawBuffers(attachments);
 }
 
 void QGraphicsContext::bindFrameBufferAttachmentHelper(GLuint fboId, const AttachmentPack &attachments)
 {
     // Set FBO attachments
-    int drawBuffers[QRenderAttachment::ColorAttachment15 + 1];
-    int i = 0;
+
     QSize fboSize;
     Q_FOREACH (const Attachment &attachment, attachments.attachments()) {
         RenderTexture *rTex = m_renderer->textureManager()->lookupResource(attachment.m_textureUuid);
@@ -346,23 +347,41 @@ void QGraphicsContext::bindFrameBufferAttachmentHelper(GLuint fboId, const Attac
                 else
                     fboSize = QSize(qMin(fboSize.width(), glTex->width()), qMin(fboSize.width(), glTex->width()));
                 m_glHelper->bindFrameBufferAttachment(glTex, attachment);
-                if (attachment.m_type <= QRenderAttachment::ColorAttachment15)
-                    drawBuffers[i++] = attachment.m_type;
             }
         }
     }
+    m_renderTargetsSize.insert(fboId, fboSize);
+}
+
+void QGraphicsContext::activateDrawBuffers(const AttachmentPack &attachments)
+{
+    int activeDrawBuffers[QRenderAttachment::ColorAttachment15 + 1];
+    int i = 0;
+
+    const QList<QRenderAttachment::RenderAttachmentType> &drawBuffers = attachments.drawBuffers();
+
+    // If drawBuffers is empty, use all the attachments as draw buffers
+    if (drawBuffers.isEmpty()) {
+        Q_FOREACH (const Attachment &attachment, attachments.attachments())
+            if (attachment.m_type <= QRenderAttachment::ColorAttachment15)
+                activeDrawBuffers[i++] = attachment.m_type;
+    } else {
+        Q_FOREACH (const QRenderAttachment::RenderAttachmentType drawBuffer, drawBuffers)
+            if (drawBuffer <= QRenderAttachment::ColorAttachment15)
+                activeDrawBuffers[i++] = drawBuffer;
+    }
+
     if (m_glHelper->checkFrameBufferComplete()) {
         if (i > 1) {// We need MRT
             if (m_glHelper->supportsFeature(QGraphicsHelperInterface::MRT)) {
                 // Set up MRT, glDrawBuffers...
-                m_glHelper->drawBuffers(i, drawBuffers);
+                m_glHelper->drawBuffers(i, activeDrawBuffers);
             }
             qDebug() << "FBO Complete";
         }
     } else {
         qWarning() << "FBO incomplete";
     }
-    m_renderTargetsSize.insert(fboId, fboSize);
 }
 
 
diff --git a/src/render/backend/qgraphicscontext_p.h b/src/render/backend/qgraphicscontext_p.h
index 6cae74612..b2796e72e 100644
--- a/src/render/backend/qgraphicscontext_p.h
+++ b/src/render/backend/qgraphicscontext_p.h
@@ -197,6 +197,7 @@ private:
     void resolveHighestOpenGLFunctions();
 
     void bindFrameBufferAttachmentHelper(GLuint fboId, const AttachmentPack &attachments);
+    void activateDrawBuffers(const AttachmentPack &attachments);
 
     bool m_initialized;
     const unsigned int m_id;
diff --git a/src/render/backend/renderview_p.h b/src/render/backend/renderview_p.h
index 029a11f62..67bb57cef 100644
--- a/src/render/backend/renderview_p.h
+++ b/src/render/backend/renderview_p.h
@@ -185,6 +185,7 @@ public:
     int frameIndex() const { return m_frameIndex; }
 
     void addRenderAttachment(Attachment attachment) { m_attachmentPack.addAttachment(attachment); }
+    void setDrawBuffers(const QList<QRenderAttachment::RenderAttachmentType> &drawBuffers) { m_attachmentPack.setDrawBuffers(drawBuffers); }
     const AttachmentPack &attachmentPack() const;
 
     void setRenderTargetHandle(HTarget renderTargetHandle) { m_renderTarget = renderTargetHandle; }