Removed old viewport draw in favour or VP2 GeometryOverride with Parallel Eval and Viewport Caching compatibility

CMakeLists.txt

@@ -16,6 +16,7 @@ find_package(Maya REQUIRED)
 find_package(OpenGL REQUIRED)
 
 set(SOURCE_FILES
+    "src/drawOverride.h"
     "src/twistSpline.h"
     "src/twistSpline_maya.h"
     "src/twistSplineData.h"
@@ -26,14 +27,15 @@ set(SOURCE_FILES
     "src/twistTangentNode.h"
 
     "src/pluginMain.cpp"
+    "src/drawOverride.cpp"
     "src/twistSplineData.cpp"
     "src/twistSplineNode.cpp"
     "src/riderConstraint.cpp"
     "src/twistTangentNode.cpp"
 )
 
 add_library(${PROJECT_NAME} SHARED ${SOURCE_FILES})
-target_include_directories(${PROJECT_NAME} 
+target_include_directories(${PROJECT_NAME}
     PRIVATE Maya::Maya
     PUBLIC "${CMAKE_CURRENT_BINARY_DIR}" "${CMAKE_CURRENT_SOURCE_DIR}"
 )

src/drawOverride.cpp

@@ -0,0 +1,185 @@
+#include "drawOverride.h"
+
+TwistSplineGeometryOverride::TwistSplineGeometryOverride(const MObject& obj)
+	: MPxGeometryOverride(obj), mTwistSplineNode(nullptr) {
+	MStatus status;
+	MFnDependencyNode dependNode(obj, &status);
+	if (status != MStatus::kSuccess) return;
+
+	MPxNode* twistSplineNode = dependNode.userNode(&status);
+	if (status != MStatus::kSuccess) twistSplineNode = nullptr;
+
+	mTwistSplineNode = dynamic_cast<TwistSplineNode*>(twistSplineNode);
+}
+
+TwistSplineGeometryOverride::~TwistSplineGeometryOverride() {}
+
+void TwistSplineGeometryOverride::updateDG() {
+	/*
+		Pull (evaluate) all attributes in TwistSplineNodeNode node we will be
+		using. Here is the list of attributes we are pulling :
+		- geometryChanging: Needed by requiresGeometryUpdate() to check if we
+		   needs to update the vertex and index buffer;
+		- debugDisplay: Needed by addUIDrawables() to draw debug mode;
+		- debugScale: Needed by addUIDrawables() to draw debug mode scale;
+		- outputSpline: Needed by addUIDrawables() to draw the main spline;
+
+		It is very important that all the attributes pulled from this method are
+		cached (with Technique 1) otherwise Evaluation Cache will not work. In
+		fact, this method is not needed by EM Evaluation modes.
+	*/
+	mTwistSplineNode->updateRenderAttributes();
+}
+
+bool TwistSplineGeometryOverride::requiresUpdateRenderItems(
+	const MDagPath& path) const {
+	/*
+		Override this function if you need a more complicated animated-material
+		behavior For example, you will need to change this to `return true` if
+		object's associated shader is changing at every frame. (This could be
+		very expensive).
+
+		Note 1: this method have to return 'false' in most case, otherwise
+		VP2 caching may not work.
+
+		Note 2: for rendering simple animated-material like animated-color or
+		animated-texture-uv check FootPrintGeometryOverrideAnimatedMaterial
+		example.
+	*/
+	return false;
+}
+
+//---------------------------------------------------------------------------
+//---------------------------------------------------------------------------
+// Geometry update and VP2 cache implementations
+//---------------------------------------------------------------------------
+//---------------------------------------------------------------------------
+
+/*
+	Return true when the aOutputSpline changes, which requires us to re-generate
+   the geometry.
+
+   Note: this method must return the exact same value in a cache-restoration
+   frame as it was in the corresponding cache-store frame.
+*/
+bool TwistSplineGeometryOverride::requiresGeometryUpdate() const {
+	/*
+		Checking the "TwistSplineNodeNode::geometryChanging" attribute if any
+		attribute affecting the geometry is changing,
+		"TwistSplineNodeNode::geometryChanging" should be affected and dirtied.
+		Also check TwistSplineNodeNodometry(). Warning: this method may be
+		called outside of regular { update() : cleanUp() } scope. Thus, we must
+		invoke node-local evaluation to ensure the correctness.
+	*/
+	return mTwistSplineNode->isGeometryChanging();
+}
+
+// Generate the geometry(vertex / index) from TwistSplineNodeNode's parameter
+// data
+// [[ensure : requiresGeometryUpdate() == false]]
+void TwistSplineGeometryOverride::populateGeometry(
+	const MGeometryRequirements& requirements,
+	const MRenderItemList& renderItems, MGeometry& data) {
+	// This call will ensure the post-condition that requiresGeometryUpdate() is
+	// false
+	mTwistSplineNode->updatingGeometry();
+}
+
+void TwistSplineGeometryOverride::addUIDrawables(
+	const MDagPath& path, MHWRender::MUIDrawManager& drawManager,
+	const MHWRender::MFrameContext& frameContext) {
+	// Retrieve the spline data to draw elements;
+	auto splineData = mTwistSplineNode->getSplineData();
+	auto splinePoints = splineData->getPoints();
+
+	bool debugDraw;
+	double debugScale;
+	mTwistSplineNode->getDebugDraw(debugDraw, debugScale);
+
+	MFnDependencyNode node(path.node());
+	bool draw2D = false;  // ALWAYS false
+
+	drawManager.beginDrawable(MUIDrawManager::kSelectable);
+
+	// Get correct color based on the state of object, e.g. active or
+	// dormant.
+	MHWRender::DisplayStatus displayStatus =
+		MHWRender::MGeometryUtilities::displayStatus(path);
+	MColor color = MHWRender::MGeometryUtilities::wireframeColor(path);
+	drawManager.setColor(color);
+	drawManager.lineStrip(splinePoints, draw2D);
+
+	if (debugDraw) {
+		MPointArray tangents;
+		MVectorArray tans = splineData->getTangents();
+		tangents.setLength(tans.length() * 2);
+		for (size_t i = 0; i < tans.length(); ++i) {
+			MPoint& spi = splinePoints[i];
+			tangents[2 * i] = spi;
+			tangents[(2 * i) + 1] = debugScale * tans[i] + spi;
+		}
+		drawManager.setColor(MColor(.5, 0, 0));
+		drawManager.lineList(tangents, draw2D);
+
+		MPointArray normals;
+		MVectorArray norms = splineData->getNormals();
+		normals.setLength(norms.length() * 2);
+		for (size_t i = 0; i < norms.length(); ++i) {
+			MPoint& spi = splinePoints[i];
+			MVector& nn = norms[i];
+			normals[2 * i] = spi;
+			normals[(2 * i) + 1] = debugScale * nn + spi;
+		}
+		drawManager.setColor(MColor(0, .5, 0));
+		drawManager.lineList(normals, draw2D);
+
+		MPointArray binormals;
+		MVectorArray binorms = splineData->getBinormals();
+		binormals.setLength(binorms.length() * 2);
+		for (size_t i = 0; i < binorms.length(); ++i) {
+			MPoint& spi = splinePoints[i];
+			binormals[2 * i] = spi;
+			binormals[(2 * i) + 1] = debugScale * binorms[i] + spi;
+		}
+		drawManager.setColor(MColor(0, 0, .5));
+		drawManager.lineList(binormals, draw2D);
+	}
+	drawManager.endDrawable();
+}
+
+//---------------------------------------------------------------------------
+//---------------------------------------------------------------------------
+// Debug functions
+//---------------------------------------------------------------------------
+//---------------------------------------------------------------------------
+
+// Return true if internal tracing is desired.
+bool TwistSplineGeometryOverride::traceCallSequence() const {
+	/*
+		Tracing will look something like the following when in shaded mode (on
+		selection change):
+		- TwistSplineGeometryOverride: Geometry override DG update: twistSpline1
+		- TwistSplineGeometryOverride: Start geometry override render item
+	   update: |transform1|twistSpline1
+		- TwistSplineGeometryOverride: - Call API to update render items
+		- TwistSplineGeometryOverride: End geometry override render item update:
+		|transform1|twistSpline1
+		- TwistSplineGeometryOverride: End geometry override clean up:
+		twistSpline1
+
+		This is based on the existing stream and indexing dirty flags being used
+		which attempts to minimize the amount of render item, vertex buffer and
+		indexing update.
+	*/
+	return false;
+}
+
+inline void TwistSplineGeometryOverride::handleTraceMessage(
+	const MString& message) const {
+	MGlobal::displayInfo(gPluginNodeMessagePrefix + message);
+
+	// Some simple custom message formatting.
+	fputs(gPluginNodeMessagePrefix, stderr);
+	fputs(message.asChar(), stderr);
+	fputs("\n", stderr);
+}

src/drawOverride.h

@@ -0,0 +1,142 @@
+#ifndef DRAW_OVERRIDE_H
+#define DRAW_OVERRIDE_H
+
+#include <maya/M3dView.h>
+#include <maya/MDrawRegistry.h>
+#include <maya/MHWGeometry.h>
+#include <maya/MHWGeometryUtilities.h>
+#include <maya/MPxGeometryOverride.h>
+#include <maya/MShaderManager.h>
+#include <maya/MSharedPtr.h>
+#include <maya/MUserData.h>
+#include <maya/MViewport2Renderer.h>
+
+#include "twistSplineNode.h"
+
+static const MString WireframeItemName = "twistSplineWires";
+
+/*
+	Customized rendering logic of TwistSplineNodeNode
+
+	This class is responsible for generating the geometry (vertex buffer) from
+	the procedure geometry. Beside rendering, the functions for generating
+	geometry is also a crucial part in Viewport Caching (in contrast with
+	Evaluation Caching).
+*/
+class TwistSplineGeometryOverride : public MPxGeometryOverride {
+   public:
+	static MPxGeometryOverride* Creator(const MObject& obj) {
+		return new TwistSplineGeometryOverride(obj);
+	}
+	~TwistSplineGeometryOverride() override;
+
+	// Support configuration functions :
+	MHWRender::DrawAPI supportedDrawAPIs() const override {
+		return (MHWRender::DrawAPI::kOpenGL | MHWRender::DrawAPI::kDirectX11 |
+				MHWRender::DrawAPI::kOpenGLCoreProfile);
+	}
+	bool supportsEvaluationManagerParallelUpdate() const override {
+		return true;
+	}
+	/*
+		Supporting Viewport Caching (VP2 Custom Caching)
+
+		Viewport Cache for customize rendering nodes is caching the geometry
+		data generated by MPxGeometryOverride::populateGeometry(). Like the
+		graphics API, the geometry data is usually expressed in three different
+		objects:
+		- Vertex Buffer : Viewport Cache
+		- Index Buffer : No cache, must be time-independent
+		- Uniform Buffer : Evaluation Cache
+		Currently, *only* Vertex Buffer can be cached in Viewport Cache and all
+		the data in Uniform Buffer (shader parameters such as Color), must be
+		stored in Evaluation Cache.
+
+		Viewport Caching is helpful if you are generating the geometry data in
+		CPU. For GPU generated geometry, the benefit is limited. To make the
+		Viewport caching works properly the following constraints must be meet:
+		- requiresUpdateRenderItems(path) always return 'false' in
+		background-dg-context.
+		- requiresGeometryUpdate() always return 'true' when restored from
+		cache (if geometry is animated).
+		- populateGeometry() should be context-safe
+	*/
+	bool supportsVP2CustomCaching() const override { return true; }
+
+	/*
+		Interaction with TwistSplineNodeNode
+		- This is the only method where you can call MPlug::getValue() or
+		Mdatablock::inputValue()
+		- This method can be empty (in EM modes), if you have setup the node
+		correctly with Technique 1.
+	*/
+	void updateDG() override;
+	// For the best practice, this method should contain no status data
+	void cleanUp() override{};
+
+	// Render item functions, only involved in foreground rendering, should
+	// not affect VP2 Caching at all
+	bool requiresUpdateRenderItems(const MDagPath& path) const override;
+	void updateRenderItems(const MDagPath& path,
+						   MRenderItemList& list) override{};
+	bool hasUIDrawables() const override { return true; };
+	void addUIDrawables(const MDagPath& path, MUIDrawManager& drawManager,
+						const MFrameContext& frameContext) override;
+
+	// Geometry update functions, major entry for support VP2 Custom Caching
+	bool requiresGeometryUpdate() const override;
+	bool isIndexingDirty(const MRenderItem& item) override {
+		return false;
+	}  // Viewport Caching does not support index buffer change (animated
+	   // topology)
+	void populateGeometry(const MGeometryRequirements& requirements,
+						  const MRenderItemList& renderItems,
+						  MGeometry& data) override;
+
+	// Debugging functions
+	bool traceCallSequence() const override;
+	void handleTraceMessage(const MString& message) const override;
+
+   private:
+	TwistSplineGeometryOverride(const MObject& obj);
+	/*
+	To ensure the plugin works well with Viewport and Evaluation Caching
+	we recommend to use a state-less MpxGeometryOverride:
+
+	- Store all time-dependent data on the attributes of corresponding Maya
+	node, instead of a data member in MpxGeometryOverride.
+	- updateDG() pulls (evaluates) all the time-dependent data on node by
+	"MDataBlock::inputValue()", but *not* store them in a data member of
+	MPxGeometryOverride
+	- Always access the time-dependent data by "MDataBlock::outputValue()"
+	in the renderer
+
+	Backgrounds of the recommendation:
+
+	In this plugin example, we have 3 different pipeline stages involved:
+		1. Node Evaluation
+		2. Geometry Update (MPxGeometryOverride invocation)
+		3. Rendering (Shader-pre-draw-callback invocation)
+
+	With (Evaluation or Viewport) Caching, some surprising mixture of
+	stages happen concurrently:
+
+	- Foreground thread :
+	MPxGeometryOverride -> Shader Callback -> (Rendering on frame 10)
+	- Background thread :
+	Node Evaluation -> MPxGeometryOverride -> (Viewport cache fill on frame 20)
+
+	Accessing the same data directly cross stage boundaries can cause
+	incorrect result or even crash Maya. Thus we must use different storage
+	for each data in each DG context (frame). And a depend node's attribute
+	are always isolated for different context.
+
+	Beside, within the MPxGeometryOverride invocation stage, it is not
+	always safe to access its data member : During Viewport Cache
+	Restoration, requiresGeometryUpdate() is the only method get called.
+	(No updateDG() call) Thus the data must be stored in the node.
+	*/
+	TwistSplineNode* mTwistSplineNode;	// The node we are rendering
+};
+
+#endif