Fix: Do not enforce TextureImage to be parented only by Texture

This behavior prevented using TextureImage not directly parented by the
Texture that uses them (assert would be triggered). In turn, this also
prevents sharing a TextureImage among several Texture instances which is
counter productive since this is where the data is actually stored.

This patch fixes this issue. It removes all direct coupling between Texture
and TextureImages. Now Texture only contains the list of TextureImage ids it
references. This allows to not make look-ups into the TextureImageManager to
retrieve handles, which could be an issue if TextureImages have not yet had
their backend created. TextureImage doesn't keep track of the referencing texture
that uses it anymore. Instead, we let the renderer do the job of checking if any of
the TextureImage referenced by a Texture has changed to trigger actual Texture
update.

Change-Id: I3c63379d0f4b314e9b53f225870eeaded0bb4aec
Task-number: QTBUG-69407
Reviewed-by: Mike Krus <mike.krus@kdab.com>

1 files changed, 33 insertions, 4 deletions

diff --git a/src/render/renderers/opengl/renderer/renderer.cpp b/src/render/renderers/opengl/renderer/renderer.cpp
index 1e0a43b30..904527cd5 100644
--- a/src/render/renderers/opengl/renderer/renderer.cpp
+++ b/src/render/renderers/opengl/renderer/renderer.cpp
@@ -1057,13 +1057,42 @@ void Renderer::lookForDownloadableBuffers()
 // Executed in a job
 void Renderer::lookForDirtyTextures()
 {
-    const QVector<HTexture> activeTextureHandles = m_nodesManager->textureManager()->activeHandles();
+    // To avoid having Texture or TextureImage maintain relationships between
+    // one another, we instead perform a lookup here to check if a texture
+    // image has been updated to then notify textures referencing the image
+    // that they need to be updated
+    TextureImageManager *imageManager = m_nodesManager->textureImageManager();
+    const QVector<HTextureImage> activeTextureImageHandles = imageManager->activeHandles();
+    Qt3DCore::QNodeIdVector dirtyImageIds;
+    for (const HTextureImage &handle: activeTextureImageHandles) {
+        TextureImage *image = imageManager->data(handle);
+        if (image->isDirty()) {
+            dirtyImageIds.push_back(image->peerId());
+            image->unsetDirty();
+        }
+    }
+
+    TextureManager *textureManager = m_nodesManager->textureManager();
+    const QVector<HTexture> activeTextureHandles = textureManager->activeHandles();
     for (const HTexture &handle: activeTextureHandles) {
-        Texture *texture = m_nodesManager->textureManager()->data(handle);
+        Texture *texture = textureManager->data(handle);
+        const QNodeIdVector imageIds = texture->textureImageIds();
+
+        // Does the texture reference any of the dirty texture images?
+        for (const QNodeId imageId: imageIds) {
+            if (dirtyImageIds.contains(imageId)) {
+                texture->addDirtyFlag(Texture::DirtyImageGenerators);
+                break;
+            }
+        }
+
         // Dirty meaning that something has changed on the texture
         // either properties, parameters, generator or a texture image
         if (texture->dirtyFlags() != Texture::NotDirty)
             m_dirtyTextures.push_back(handle);
+        // Note: texture dirty flags are reset when actually updating the
+        // textures in updateGLResources() as resetting flags here would make
+        // us lose information about what was dirty exactly.
     }
 }
 
@@ -1204,7 +1233,7 @@ void Renderer::updateGLResources()
 void Renderer::updateTexture(Texture *texture)
 {
     // Check that the current texture images are still in place, if not, do not update
-    const bool isValid = texture->isValid();
+    const bool isValid = texture->isValid(m_nodesManager->textureImageManager());
     if (!isValid)
         return;
 
@@ -1278,7 +1307,7 @@ void Renderer::updateTexture(Texture *texture)
 
     // Will make the texture requestUpload
     if (dirtyFlags.testFlag(Texture::DirtyImageGenerators) &&
-            !glTextureManager->setImages(glTexture, texture->textureImages()))
+            !glTextureManager->setImages(glTexture, texture->textureImageIds()))
         qWarning() << "[Qt3DRender::TextureNode] updateTexture: TextureImpl.setGenerators failed, should be non-shared";
 
     // Will make the texture requestUpload