Merge pull request #70663 from EpEpDragon/feature_buffer_get_data_size_option

Add optional size parameter to the RenderDevice buffer_get_data method.

doc/classes/RenderingDevice.xml

@@ -32,7 +32,10 @@
 		<method name="buffer_get_data">
 			<return type="PackedByteArray" />
 			<param index="0" name="buffer" type="RID" />
+			<param index="1" name="offset_bytes" type="int" default="0" />
+			<param index="2" name="size_bytes" type="int" default="0" />
 			<description>
+				Returns a copy of the data of the specified [param buffer], optionally [param offset_bytes] and [param size_bytes] can be set to copy only a portion of the buffer.
 			</description>
 		</method>
 		<method name="buffer_update">

drivers/vulkan/rendering_device_vulkan.cpp

@@ -5927,7 +5927,7 @@ Error RenderingDeviceVulkan::buffer_clear(RID p_buffer, uint32_t p_offset, uint3
 	return OK;
 }
 
-Vector<uint8_t> RenderingDeviceVulkan::buffer_get_data(RID p_buffer) {
+Vector<uint8_t> RenderingDeviceVulkan::buffer_get_data(RID p_buffer, uint32_t p_offset, uint32_t p_size) {
 	_THREAD_SAFE_METHOD_
 
 	// It could be this buffer was just created.
@@ -5944,12 +5944,20 @@ Vector<uint8_t> RenderingDeviceVulkan::buffer_get_data(RID p_buffer) {
 
 	VkCommandBuffer command_buffer = frames[frame].setup_command_buffer;
 
+	// Size of buffer to retrieve.
+	if (!p_size) {
+		p_size = buffer->size;
+	} else {
+		ERR_FAIL_COND_V_MSG(p_size + p_offset > buffer->size, Vector<uint8_t>(),
+				"Size is larger than the buffer.");
+	}
+
 	Buffer tmp_buffer;
-	_buffer_allocate(&tmp_buffer, buffer->size, VK_BUFFER_USAGE_TRANSFER_DST_BIT, VMA_MEMORY_USAGE_AUTO_PREFER_HOST, VMA_ALLOCATION_CREATE_HOST_ACCESS_RANDOM_BIT);
+	_buffer_allocate(&tmp_buffer, p_size, VK_BUFFER_USAGE_TRANSFER_DST_BIT, VMA_MEMORY_USAGE_AUTO_PREFER_HOST, VMA_ALLOCATION_CREATE_HOST_ACCESS_RANDOM_BIT);
 	VkBufferCopy region;
-	region.srcOffset = 0;
+	region.srcOffset = p_offset;
 	region.dstOffset = 0;
-	region.size = buffer->size;
+	region.size = p_size;
 	vkCmdCopyBuffer(command_buffer, buffer->buffer, tmp_buffer.buffer, 1, &region); // Dst buffer is in CPU, but I wonder if src buffer needs a barrier for this.
 	// Flush everything so memory can be safely mapped.
 	_flush(true);
@@ -5960,9 +5968,9 @@ Vector<uint8_t> RenderingDeviceVulkan::buffer_get_data(RID p_buffer) {
 
 	Vector<uint8_t> buffer_data;
 	{
-		buffer_data.resize(buffer->size);
+		buffer_data.resize(p_size);
 		uint8_t *w = buffer_data.ptrw();
-		memcpy(w, buffer_mem, buffer->size);
+		memcpy(w, buffer_mem, p_size);
 	}
 
 	vmaUnmapMemory(allocator, tmp_buffer.allocation);

drivers/vulkan/rendering_device_vulkan.h

@@ -1122,7 +1122,7 @@ public:
 
 	virtual Error buffer_update(RID p_buffer, uint32_t p_offset, uint32_t p_size, const void *p_data, BitField<BarrierMask> p_post_barrier = BARRIER_MASK_ALL_BARRIERS); // Works for any buffer.
 	virtual Error buffer_clear(RID p_buffer, uint32_t p_offset, uint32_t p_size, BitField<BarrierMask> p_post_barrier = BARRIER_MASK_ALL_BARRIERS);
-	virtual Vector<uint8_t> buffer_get_data(RID p_buffer);
+	virtual Vector<uint8_t> buffer_get_data(RID p_buffer, uint32_t p_offset = 0, uint32_t p_size = 0);
 
 	/*************************/
 	/**** RENDER PIPELINE ****/

servers/rendering/rendering_device.cpp

@@ -746,7 +746,7 @@ void RenderingDevice::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("buffer_update", "buffer", "offset", "size_bytes", "data", "post_barrier"), &RenderingDevice::_buffer_update, DEFVAL(BARRIER_MASK_ALL_BARRIERS));
 	ClassDB::bind_method(D_METHOD("buffer_clear", "buffer", "offset", "size_bytes", "post_barrier"), &RenderingDevice::buffer_clear, DEFVAL(BARRIER_MASK_ALL_BARRIERS));
-	ClassDB::bind_method(D_METHOD("buffer_get_data", "buffer"), &RenderingDevice::buffer_get_data);
+	ClassDB::bind_method(D_METHOD("buffer_get_data", "buffer", "offset_bytes", "size_bytes"), &RenderingDevice::buffer_get_data, DEFVAL(0), DEFVAL(0));
 
 	ClassDB::bind_method(D_METHOD("render_pipeline_create", "shader", "framebuffer_format", "vertex_format", "primitive", "rasterization_state", "multisample_state", "stencil_state", "color_blend_state", "dynamic_state_flags", "for_render_pass", "specialization_constants"), &RenderingDevice::_render_pipeline_create, DEFVAL(0), DEFVAL(0), DEFVAL(TypedArray<RDPipelineSpecializationConstant>()));
 	ClassDB::bind_method(D_METHOD("render_pipeline_is_valid", "render_pipeline"), &RenderingDevice::render_pipeline_is_valid);

servers/rendering/rendering_device.h

@@ -828,7 +828,7 @@ public:
 
 	virtual Error buffer_update(RID p_buffer, uint32_t p_offset, uint32_t p_size, const void *p_data, BitField<BarrierMask> p_post_barrier = BARRIER_MASK_ALL_BARRIERS) = 0;
 	virtual Error buffer_clear(RID p_buffer, uint32_t p_offset, uint32_t p_size, BitField<BarrierMask> p_post_barrier = BARRIER_MASK_ALL_BARRIERS) = 0;
-	virtual Vector<uint8_t> buffer_get_data(RID p_buffer) = 0; //this causes stall, only use to retrieve large buffers for saving
+	virtual Vector<uint8_t> buffer_get_data(RID p_buffer, uint32_t p_offset = 0, uint32_t p_size = 0) = 0; // This causes stall, only use to retrieve large buffers for saving.
 
 	/******************************************/
 	/**** PIPELINE SPECIALIZATION CONSTANT ****/