// Shave and a Haircut
// (c) 2019 Epic Games
// US Patent 6720962

#include <maya/MFnDependencyNode.h>
#include <maya/MGlobal.h>
#include <maya/MItDependencyNodes.h>
#include <maya/MObjectArray.h>

#include "shaveDebug.h"

#include "shaveCheckObjectVisibility.h"
#include "shaveConstant.h"
#include "shaveGlobals.h"
#include "shaveHairShape.h"
#include "shaveMaya.h"
#include "shaveRender.h"
#include "shaveRenderer.h"
#include "shaveSDKFUNCS.h"
#include "shaveTextureStore.h"
#include "shaveUtil.h"


shaveRenderer::shaveRenderer()
:	mRendering(false)
,	mWarningGivenInvalidHairMode(false)
,	mWarningGivenInvalidInstanceMode(false)
{}


shaveRenderer::~shaveRenderer()
{}


void shaveRenderer::doShutter(
		const MTime& curTime, shaveConstant::ShutterState shutter
)
{
	ENTER();

	if ((mGeometryNodes.length() > 0) || (mNonGeometryNodes.length() > 0))
	{
		float	frame = (float)curTime.as(MTime::uiUnit());

		shaveGlobals::getGlobals();
		shaveMaya::getRenderGlobals();

		//
		// We "render" geometry by having the shaveHairShape create its entire
		// mesh.  As such, we want it in the scene before anything else
		// happens so that Maya will take it into account when doing
		// bounding box calculations for the render.
		//
		if (mGeometryNodes.length() > 0)
			shaveRender::geomRender(mGeometryNodes);

		MDagPath	cameraPath = shaveRender::getRenderCamPath();

		if (mNonGeometryNodes.length() > 0)
		{
			//
			// Create the texture lookup table for this frame.
			//
			// We only do this on shutterOpen, not shutterClose.  The
			// reason for this is that Shave doesn't handle animation of
			// any of its parameters: it simply takes their value at
			// shutter close.  So we only need to create the lookups once
			// per frame, even when motion blur is on.
			//
			// That would argue that we should create the lookup on
			// shutterClose, not shutterOpen.  However, two things mitigate
			// against that.  First, to properly support vertex shaders, we
			// need to have vertex-level colour info available at both
			// shutterOpen and shutterClose.  Second, there is a bug in
			// Maya that if you sample a shading network on shutterClose,
			// it screws up other, unrelated textures in the scene.
			//
			// Okay, so the last thing to discuss is why we don't create
			// the lookup table in frameStart().  That's because there's a
			// bug in Mental Ray For Maya such that the frame number at
			// frameStart() is not correct during a batch render.  So
			// instead we have to wait for the actual time change before we
			// can know which frame we are rendering. We no longer support
            // Mental Ray, but it seems safer to leave it as-is in case
            // any other renderers suffer from the same problem.
			//
			if ((shutter == shaveConstant::kShutterOpen)
			||	(shutter == shaveConstant::kShutterBoth))
			{
#ifdef PER_NODE_TEXLOOKUP
				initTexInfoLookup2(
					mNonGeometryNodes,
					"",
					shaveRender::getFrameGlobals().verbose
				);
#else
				initTexInfoLookup(
					mNonGeometryNodes,
					"",
					shaveRender::getFrameGlobals().verbose
				);
#endif
			}

			shaveRender::buildHairStack(mNonGeometryNodes, shutter);
		}

		//
		// Call the overridden render() method.
		//
		render(frame, shutter, cameraPath);
	}

	LEAVE();
}


void shaveRenderer::frameEnd(const shaveGlobals::Globals& g)
{
	shaveRender::clearHairStack(mNonGeometryNodes);
	mGeometryNodes.clear();
	mNonGeometryNodes.clear();
}


void shaveRenderer::frameStart(const shaveGlobals::Globals& g)
{
	SHAVEset_tile_limit((int)g.tileMemoryLimit, (int)g.transparencyDepth);

	//
	// Get the nodes to be rendered as geometry, and those to be rendered
	// not as geometry, into two separate lists.
	//
	mGeometryNodes.clear();
	mNonGeometryNodes.clear();

	getRenderableShaveNodesByRenderMode(&mGeometryNodes, &mNonGeometryNodes);

	//
	// Changes in animated attributes may have changed the list of
	// renderable shaveHairShapes.  Let's update the flags telling us which
	// types of shaveHairShapes we have.
	//
	bool	tempHaveHair;
	bool	tempHaveInstances;

	shaveUtil::classifyShaveNodes(mGeometryNodes, tempHaveHair, tempHaveInstances);
	shaveUtil::classifyShaveNodes(mNonGeometryNodes, mHaveHair, mHaveInstances);

	mHaveHair = (mHaveHair || tempHaveHair);
	mHaveInstances = (mHaveInstances || tempHaveInstances);
}


//
// Return the base render modes, without caring if we actually have any of
// the relevant types of shaveHairShape.
//
shaveConstant::RenderMode shaveRenderer::getBaseRenderMode(
	bool* renderInstances
) const
{
	shaveConstant::RenderMode	hairRenderMode;

	hairRenderMode = normalRenderModeGlob;

	if (renderInstances) *renderInstances = enableInstanceGeometryGlob;

	//
	// If the specified render mode does not exist, then switch to buffer.
	//
	if (shaveRender::getRenderModeName(hairRenderMode) == "")
	{
		if (!mWarningGivenInvalidHairMode)
		{
			MGlobal::displayWarning(
				MString("Shave: Hair render mode ") + (double)hairRenderMode
				+ " is invalid.  Using "
				+ shaveRender::getRenderModeName(shaveConstant::kBufferRender)
				+ " render mode instead."
			);

			mWarningGivenInvalidHairMode = true;
		}

		hairRenderMode = shaveConstant::kBufferRender;
	}

	return hairRenderMode;
}


shaveConstant::ShadowSource shaveRenderer::getBaseShadowSource() const
{
	ENTER();

	shaveConstant::ShadowSource	hairShadowSource = shaveConstant::kNoShadows;
	shaveConstant::RenderMode	hairRenderMode = getRenderMode();

	if (doHairShadowsGlob)
	{
		switch (hairRenderMode)
		{
			case shaveConstant::kNoRender:
			break;

			case shaveConstant::kGeometryRender:
				hairShadowSource = shaveConstant::kMayaGeomShadows;
			break;

			default:
				if (shaveUseGeomShadowsGlob)
					hairShadowSource = shaveConstant::kMayaGeomShadows;
				else
					hairShadowSource = shaveConstant::kShaveShadows;
			break;
		}
	}

	//
	// Return the shadow sources to the caller.
	//
	RETURN(hairShadowSource);
}


//
// Return the render modes applicable to the given array of shaveHairShapes.
//
shaveConstant::RenderMode shaveRenderer::getFilteredRenderMode(
		const MObjectArray& shaveHairShapes, bool* renderInstances
) const
{
	//
	// Get the base mode.
	//
	shaveConstant::RenderMode	hairRenderMode = getRenderMode(renderInstances);

	//
	// Do we have any hair?  Any instances?
	//
	bool			haveHair = false;
	bool			haveInstances = false;

	shaveUtil::classifyShaveNodes(shaveHairShapes, haveHair, haveInstances);

	if (!haveInstances && renderInstances) *renderInstances = false;
	if (!haveHair) hairRenderMode = shaveConstant::kNoRender;

	return hairRenderMode;
}


void shaveRenderer::getGeomVisibility(
	bool& hairPrimaryVisibility,
	bool& hairSecondaryVisibility,
	bool& instancePrimaryVisibility,
	bool& instanceSecondaryVisibility
)
{
	bool						renderInstances;
	shaveConstant::RenderMode	hairRenderMode;
	shaveConstant::ShadowSource	hairShadowSource;

	hairRenderMode = getRenderMode(&renderInstances);
	hairShadowSource = getShadowSource();

	switch (hairRenderMode)
	{
		case shaveConstant::kGeometryRender:
			hairPrimaryVisibility = true;
			hairSecondaryVisibility = true;
		break;

		case shaveConstant::kBufferRender:
			hairPrimaryVisibility = false;
			hairSecondaryVisibility =
					(hairShadowSource == shaveConstant::kMayaGeomShadows);
		break;

		case shaveConstant::kNoRender:
		default:
			hairPrimaryVisibility = false;
			hairSecondaryVisibility = false;
		break;
	}

	instancePrimaryVisibility = renderInstances;
	instanceSecondaryVisibility = renderInstances;
}


float shaveRenderer::getPixelAspect() const
{
	return	((float)shaveMaya::imageHeight
				/ (float)shaveMaya::imageWidth)
				* shaveMaya::deviceAspectRatio;
}


// Returns an array of those shaveHairShapes which are in an appropriate state
// to be rendered (e.g. active, visible, etc).
//
void shaveRenderer::getRenderableShaveNodes(MObjectArray& shaveHairShapes)
{
    shaveHairShapes.clear();

    // Get the base render modes.
    //
    bool                        includeInstances;
    shaveConstant::RenderMode    renderMode = getRenderMode(&includeInstances);

    const bool    includeHair = (renderMode != shaveConstant::kNoRender);

    // If the render modes are excluding both hair and instances, then we're
    // done.
    //
    if (!includeHair && !includeInstances) return;

    // Run through all the shaveHairShapes in the scene and save the ones which
    // are renderable.
    //
    MItDependencyNodes iter;

    for (; !iter.isDone(); iter.next())
    {
        MObject           node = iter.item();
        MFnDependencyNode nodeFn(node);

        if (nodeFn.typeId() != shaveHairShape::id) continue;

        shaveHairShape* nodePtr = (shaveHairShape*)nodeFn.userNode();

        //
        // Skip any nodes whose render mode means that they're not being
        // rendered.
        //
        bool    isInstanced = nodePtr->isInstanced();

        if ((isInstanced && !includeInstances)
        ||  (!isInstanced && !includeHair))
        {
            continue;
        }

        //  Skip any nodes which are not visible.
        //
        //  TODO:   The user may have turned off visibility on the
        //          hair node or its display node. The display node
        //          only matters when we're displaying hair as geometry,
        //          but it would be confusing to force our users to
        //          switch back and forth between the hair and display
        //          nodes, depending upon which render mode they were
        //          using. To avoid that we go with a least common
        //          denominator approach: both the hair and display
        //          nodes must be visible for the hair to render.
        //
        MDagPath path;
        MDagPath::getAPathTo(node, path);

        if (areObjectAndParentsVisible(path, false, true))
        {
            // Find the shaveHairShape's display node.
            //
            MObject displayNode = nodePtr->getDisplayShape();

            if (displayNode.isNull()) continue;

            // Is the display node in a renderable layer?
            //
            MFnDagNode dagNodeFn(displayNode);
            MPlug      plug = dagNodeFn.findPlug("layerRenderable");
            bool       layerIsRenderable;

            plug.getValue(layerIsRenderable);

            if (!layerIsRenderable) continue;

            // Get a DAG path to the display node.  At the moment we don't
            // support instancing of shaveHairShapes, or their display
            // nodes, so any path will do.
            //
            dagNodeFn.getPath(path);

            // We only render shaveHairShapes whose display nodes are
            // visible.
            //
            // This method used to discard those shaveHairShapes whose
            // display nodes had their primary visibility off.  However, if
            // someone turns off a node's primary visibility while leaving
            // its regular visibility on, that means that they still want
            // it to show up in shadows, reflections, refractions, etc.  So
            // we really do still need to render it.  Admittedly we might
            // not want it to be seen in a buffer render, but that's a
            // larger issue than we can resolve here with a simply binary
            // check of primary visibility.  So now we ignore primary
            // visibility when checking display nodes.
            //
            if (areObjectAndParentsVisible(path, false, true))
                shaveHairShapes.append(node);
        }
    }
}


//
// Returns those shaveHairShapes which are in an appropriate state to be
// rendered (e.g. active, visible, etc).  The result is returned as two
// arrays, one containing those shaveHairShapes which are to be rendered as
// normal Maya geometry, and another containing those which require
// rendering by Shave.  (The latter includes geometry shaders using Shave
// calls to generate render geometry.)
//
void shaveRenderer::getRenderableShaveNodesByRenderMode(
		MObjectArray* geomNodes, MObjectArray* nonGeomNodes
)
{
	MObjectArray			shaveHairShapes;

	getRenderableShaveNodes(shaveHairShapes);

	unsigned int			i;

	for (i = 0; i < shaveHairShapes.length(); i++)
	{
		MFnDependencyNode	nodeFn(shaveHairShapes[i]);
		shaveHairShape*		nodePtr = (shaveHairShape*)nodeFn.userNode();

		//
		// Ask the renderer-specific subclass whether this node should be
		// put onto the geomNodes list.
		//
		if (isGeomNode(nodePtr))
		{
			if (geomNodes) geomNodes->append(shaveHairShapes[i]);
		}
		else
		{
			if (nonGeomNodes) nonGeomNodes->append(shaveHairShapes[i]);
		}
	}
}


shaveConstant::RenderMode shaveRenderer::getRenderMode(bool* renderInstances)
		const
{
	//
	// If we're in the middle of a render, return the cached values.
	//
	if (mRendering)
	{
		if (renderInstances) *renderInstances = mRenderInstances;

		return mHairRenderMode;
	}

	return getBaseRenderMode(renderInstances);
}


shaveConstant::ShadowSource shaveRenderer::getShadowSource() const
{
	//
	// If we're in the middle of a render, return the cached value.
	//
	if (mRendering) return mHairShadowSource;

	return getBaseShadowSource();
}


bool shaveRenderer::needVertexColours() const
{
	return false;
}


void shaveRenderer::renderEnd()
{
	//
	// Clear the various warning flags so that the warnings will be issued
	// on the next render.
	//
	mWarningGivenInvalidHairMode = false;
	mWarningGivenInvalidInstanceMode = false;

	mRendering = false;
}


void shaveRenderer::renderInterrupted()
{}


void shaveRenderer::renderStart()
{
	//
	// Cache the render and shadow modes.
	//
	MObjectArray				shaveHairShapes;

	mHairRenderMode = getRenderMode(&mRenderInstances);
	mHairShadowSource = getShadowSource();

	//
	// We have something of a problem here.  We don't want to create, say,
	// a buffer render shader if there are only instances in the scene.
	// It's easy enough to check the list of shaveHairShapes in the scene, but
	// it's possible that there might be shaveHairShapes which are present but
	// not being rendered, because their 'active' flag is false, their
	// instance geom is invisible, etc.  We can't take any of that into
	// account because the affect may be animated: thus an instance which
	// is invisible now might be visible on the next frame, so we have to
	// make sure that the shader for it is already in place.
	//
	// So we're stuck with just a static check of the nodes currently
	// available.  If subsequently during a frame we find that a particular
	// type of shader is not needed we'll have to give it a flag telling it
	// to act as a no-op for that frame.
	//
	shaveUtil::getShaveNodes(shaveHairShapes);
	shaveUtil::classifyShaveNodes(shaveHairShapes, mHaveHair, mHaveInstances);

	if (!mHaveHair)
	{
		mHairRenderMode = shaveConstant::kNoRender;
		mHairShadowSource = shaveConstant::kNoShadows;
	}

	if (!mHaveInstances) mRenderInstances = false;

	//
	// This will trigger getRenderMode() and getShadowSource() to use the
	// cached values.
	//
	mRendering = true;
}