Remove explicit checks against kp::Memory::type() (#455)

* algorithm: check DescriptorType when creating pool

The function that was prevously used, `mem->type()`, is not explicitly
the same as the descriptor type, so using `mem->getDescriptorType()` is
more accurate.

It also makes it easier to create new image-like subclasses of
`kp::Memory` because as long as they specify the correct descriptor
type, the correct pools will be created.

Signed-off-by: Anders Hellerup Madsen <anders@hellerup-madsen.dk>

* Algorithm: check type before casting

The if statement used to assume that if `mem->type() ==
memory::Type::eImage` then it was safe to assume that the memory object
is an instance of `kp::Image`. However, any subclass of `kp::Memory`
could implement the virtual `type()` method to return
`memory::Type::eImage`, so this is an invalid assumption.

This commit fixes the issue by only casting if the memory object
actually is an instance of `kp::Memory`

Signed-off-by: Anders Hellerup Madsen <anders@hellerup-madsen.dk>

---------

Signed-off-by: Anders Hellerup Madsen <anders@hellerup-madsen.dk>

Author: ahem

src/Algorithm.cpp

@@ -134,7 +134,7 @@ Algorithm::createParameters()
     KP_LOG_DEBUG("Kompute Algorithm createParameters started");
 
     for (const std::shared_ptr<Memory>& mem : this->mMemObjects) {
-        if (mem->type() == Memory::Type::eImage) {
+        if (mem->getDescriptorType() == vk::DescriptorType::eStorageImage) {
             numImages++;
         } else {
             numTensors++;

src/OpAlgoDispatch.cpp

@@ -25,9 +25,8 @@ OpAlgoDispatch::record(const vk::CommandBuffer& commandBuffer)
 
         // For images the image layout needs to be set to eGeneral before using
         // it for imageLoad/imageStore in a shader.
-        if (mem->type() == Memory::Type::eImage) {
-            std::shared_ptr<Image> image = std::static_pointer_cast<Image>(mem);
-
+        std::shared_ptr<Image> image = std::dynamic_pointer_cast<Image>(mem);
+        if (image) {
             image->recordPrimaryImageBarrier(
               commandBuffer,
               vk::AccessFlagBits::eTransferWrite,