source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/ShadowMapping.cpp @ 2917

#include "ShadowMapping.h"
#include "FrameBufferObject.h"
#include "RenderState.h"
#include "RenderTraverser.h"
#include "Light.h"
#include "Polygon3.h"
#include "Polyhedron.h"

#include <IL/il.h>
#include <assert.h>


using namespace std;


namespace CHCDemoEngine
{


static Polyhedron *polyhedron = NULL;


static void PrintGLerror(char *msg)
{
        GLenum errCode;
        const GLubyte *errStr;
        
        if ((errCode = glGetError()) != GL_NO_ERROR) 
        {
                errStr = gluErrorString(errCode);
                fprintf(stderr,"OpenGL ERROR: %s: %s\n", errStr, msg);
        }
}



static CGprogram sCgShadowProgram;
static CGparameter sShadowParam;


static void GrabDepthBuffer(float *data, GLuint depthTexture)
{
        glEnable(GL_TEXTURE_2D);
        glBindTexture(GL_TEXTURE_2D, depthTexture);

        glGetTexImage(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, GL_FLOAT, data);

        glBindTexture(GL_TEXTURE_2D, 0);
        glDisable(GL_TEXTURE_2D);
}


static void ExportDepthBuffer(float *data, int size)
{
        ilInit();
        assert(ilGetError() == IL_NO_ERROR);

        ILstring filename = ILstring("shadow.tga");
        ilRegisterType(IL_FLOAT);

        const int depth = 1;
        const int bpp = 1;

        if (!ilTexImage(size, size, depth, bpp, IL_LUMINANCE, IL_FLOAT, data))
        {
                cerr << "IL error " << ilGetError() << endl;
        
                ilShutDown();
                assert(ilGetError() == IL_NO_ERROR);

                return;
        }

        if (!ilSaveImage(filename))
        {
                cerr << "TGA write error " << ilGetError() << endl;
        }

        ilShutDown();
        assert(ilGetError() == IL_NO_ERROR);

        cout << "exported depth buffer" << endl;
}



ShadowMap::ShadowMap(Light *light, int size, const AxisAlignedBox3 &sceneBox, Camera *cam):
mSceneBox(sceneBox), mSize(size), mCamera(cam), mLight(light)
{
        mFbo = new FrameBufferObject(size, size, FrameBufferObject::DEPTH_32, true);
        // the diffuse color buffer
        mFbo->AddColorBuffer(ColorBufferObject::BUFFER_UBYTE, ColorBufferObject::WRAP_CLAMP_TO_EDGE, ColorBufferObject::FILTER_LINEAR, false);

        mShadowCam = new Camera(mSceneBox.Size().x * 0.5f, mSceneBox.Size().y * 0.5f);
        mShadowCam->SetOrtho(true);
}


ShadowMap::~ShadowMap()
{
        DEL_PTR(mFbo);
        DEL_PTR(mShadowCam);
}


void ShadowMap::DrawPolys()
{
        if (!polyhedron) return;

        for (size_t i = 0; i < polyhedron->NumPolygons(); ++ i)
        {
                float r = (float)i / polyhedron->NumPolygons();
                float g = 1;
                float b = 1;

                glColor3f(r, g, b);

                glBegin(GL_LINE_LOOP);

                Polygon3 *poly = polyhedron->GetPolygons()[i];

                for (size_t j = 0; j < poly->mVertices.size(); ++ j)
                {
                        Vector3 v = poly->mVertices[j];
                        glVertex3d(v.x, v.y, v.z);
                }

                glEnd();
        }
}


void ShadowMap::IncludeLightVolume(const Polyhedron &polyhedron, 
                                                                   VertexArray &frustumPoints, 
                                                                   const Vector3 lightDir,
                                                                   const AxisAlignedBox3 &sceneBox
                                                                   ) 
{
        // we don't need closed form anymore => just store vertices
        VertexArray vertices;
        polyhedron.CollectVertices(vertices);

        // we 'look' at each point and calculate intersections of rays with scene bounding box
        VertexArray::const_iterator it, it_end = vertices.end();

        for (it = vertices.begin(); it != it_end; ++ it)
        {
                Vector3 v  = *it;

                frustumPoints.push_back(v);
                
                // hack: get point surely outside of box
                v -= Magnitude(mSceneBox.Diagonal()) * lightDir;

                SimpleRay ray(v, lightDir);

                float tNear, tFar;

                if (sceneBox.Intersects(ray, tNear, tFar))
                {
                        Vector3 newpt = ray.Extrap(tNear);
                        frustumPoints.push_back(newpt);                 
                }
        }
}


float ShadowMap::ComputeN() const 
{
        const float n = mShadowCam->GetNear();
        const float f = mShadowCam->GetFar();

        const float d = fabs(f - n);
        
        const float dotProd = DotProd(mCamera->GetDirection(), mShadowCam->GetDirection());
        const float sinGamma = sin(fabs(acos(dotProd)));

        return (n + sqrt(n * (n + d * sinGamma))) /  sinGamma;
}


Matrix4x4 ShadowMap::CalcLispSMTransform(const Matrix4x4 &lightProjView, const AxisAlignedBox3 &extremalPoints)
{
        Matrix4x4 lispMtx;

        ///////////////
        //-- We apply the lispsm algorithm in order to calculate an optimal light projection matrix

        const float n = 1e20f;//ComputeN();

        cout << "n: " << n << endl;

        const Vector3 nearPt = mShadowCam->GetNear() * mShadowCam->GetDirection() + mShadowCam->GetPosition();

        //get the coordinates of the near camera point in light space
        const Vector3 lsNear = lightProjView * nearPt;

        //c start has the x and y coordinate of e, the z coord of B.min()
        const Vector3 startPt = Vector3(lsNear.x, lsNear.y, extremalPoints.Min().y);

        // the new projection center
        const Vector3 unit_y = Vector3(0, 1, 0);
        Vector3 projCenter = startPt - unit_y * n;

        //construct a translation that moves to the projection center
        const Matrix4x4 projectionCenter = TranslationMatrix(-projCenter);

        // light space y size
        const float d = fabs(extremalPoints.Max()[2] - extremalPoints.Min()[2]); 

        lispMtx = GetFrustum(-1.0, 1.0, -1.0, 1.0, n, n + d);

        cout << "lispsm\n" << lispMtx << endl;

        lispMtx *= projectionCenter;

        // transform into OpenGL right handed system
        Matrix4x4 scale = ScaleMatrix(1.0f, 1.0f, -1.0f);

        lispMtx *= scale;
        
        return IdentityMatrix();
}


bool ShadowMap::CalcLightProjection(Matrix4x4 &lightProj)
{
        DEL_PTR(polyhedron);


        ///////////////////
        //-- First step: calc frustum clipped by scene box

        polyhedron = CalcClippedFrustum(mSceneBox);

        if (!polyhedron) return false; // something is wrong

        // include the part of the light volume that "sees" the frustum
        // we only require frustum vertices

        VertexArray frustumPoints;
        IncludeLightVolume(*polyhedron, frustumPoints, mShadowCam->GetDirection(), mSceneBox);


        ///////////////
        //-- transform points from world view to light view and calculate extremal points

        AxisAlignedBox3 extremalPoints;
        extremalPoints.Initialize();

        Matrix4x4 lightView;
        mShadowCam->GetModelViewMatrix(lightView);

        VertexArray::const_iterator it, it_end = frustumPoints.end();
                
        for (it = frustumPoints.begin(); it != it_end; ++ it)
        {
                Vector3 pt = *it;
                pt = lightView * pt;

                extremalPoints.Include(pt);
        }

        lightProj = IdentityMatrix(); // we use directional lights

        Matrix4x4 shadowView;
        mShadowCam->GetModelViewMatrix(shadowView);

        //do Light Space Perspective shadow mapping
        //rotate the lightspace so that the proj light view always points upwards
        //calculate a frame matrix that uses the projViewDir[light-space] as up vector
        //look(from position, into the direction of the projected direction, with unchanged up-vector)
        //lightProj = Math::look<REAL>(M4(),V3::ZERO(),projViewDir,V3::UNIT_Y())*lightProj

        const Matrix4x4 matLispSM = 
                CalcLispSMTransform(shadowView * lightProj, extremalPoints);

        lightProj *= matLispSM;

        // focus projection matrix on the extremal points => scale to unit cube
        lightProj *= GetFittingProjectionMatrix(extremalPoints);

        // we have to flip the signs in order tp opengl style projection matrix
        Matrix4x4 scale = ScaleMatrix(-1, -1, -1); 
        lightProj *= scale;
        
        return true;
}


Polyhedron *ShadowMap::CalcClippedFrustum(const AxisAlignedBox3 &box) const
{
        Vector3 ftl, ftr, fbl, fbr;
        Vector3 ntl, ntr, nbl, nbr;

        VertexArray sides[6];

        mCamera->ComputePoints(ftl, ftr, fbl, fbr, ntl, ntr, nbl, nbr);

        for (int i = 0; i < 6; ++ i)
                sides[i].resize(4);
        
        // left, right
        sides[0][0] = ftl; sides[0][1] = fbl; sides[0][2] = nbl; sides[0][3] = ntl;
        sides[1][0] = fbr; sides[1][1] = ftr; sides[1][2] = ntr; sides[1][3] = nbr;
        // bottom, top
        sides[2][0] = fbl; sides[2][1] = fbr; sides[2][2] = nbr; sides[2][3] = nbl;
        sides[3][0] = ftr; sides[3][1] = ftl; sides[3][2] = ntl; sides[3][3] = ntr;
        // near, far
        sides[4][0] = ntr; sides[4][1] = ntl; sides[4][2] = nbl; sides[4][3] = nbr; 
        sides[5][0] = ftl; sides[5][1] = ftr; sides[5][2] = fbr; sides[5][3] = fbl; 

        //////////
        //-- compute polyhedron

        PolygonContainer polygons;

        for (int i = 0; i < 6; ++ i)
        {
                Polygon3 *poly = new Polygon3(sides[i]);
                polygons.push_back(poly);
        }

        Polyhedron *p = new Polyhedron(polygons);
        Polyhedron *clippedPolyhedron = box.CalcIntersection(*p);
        
        DEL_PTR(p);
        

        return clippedPolyhedron;
}


void ShadowMap::ComputeShadowMap(RenderTraverser *renderer, const Matrix4x4 &projView)
{
        const float xlen = Magnitude(mSceneBox.Diagonal() * 0.5f);
        const float ylen = Magnitude(mSceneBox.Diagonal() * 0.5f);
        
        const Vector3 dir = mLight->GetDirection();
        //const Vector3 dir(0, 0, 1);

        mShadowCam->SetDirection(dir);
        
        //cout << "lightdir: " << mShadowCam->GetDirection() << endl;

        // set position so that we can see the whole scene
        Vector3 pos = mSceneBox.Center();

        //Matrix4x4 camView;
        //mCamera->GetModelViewMatrix(camView);

        pos -= dir * Magnitude(mSceneBox.Diagonal() * 0.5f);
        mShadowCam->SetPosition(pos);

        mFbo->Bind();
        
        glDrawBuffers(1, mrt);

        glPushAttrib(GL_VIEWPORT_BIT);
        glViewport(0, 0, mSize, mSize);

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        glDisable(GL_LIGHTING);
        glDisable(GL_TEXTURE_2D);
        glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);

        glPolygonOffset(1.0f, 2000.0f);
        glEnable(GL_POLYGON_OFFSET_FILL);

        glShadeModel(GL_FLAT);
        glEnable(GL_DEPTH_TEST);

        // setup projection
        /*glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(+xlen, -xlen, +ylen, -ylen, 0.0f, Magnitude(mSceneBox.Diagonal())); 

        Matrix4x4 dummyMat;
        glGetFloatv(GL_PROJECTION_MATRIX, (float *)dummyMat.x);
        cout << "old:\n" << dummyMat << endl;
        */

        Matrix4x4 lightView, lightProj;

        mShadowCam->GetModelViewMatrix(lightView);
        CalcLightProjection(lightProj);

        glMatrixMode(GL_PROJECTION);
        glPushMatrix();
        glLoadMatrixf((float *)lightProj.x);

        mLightProjView = lightView * lightProj;

        //cout << "new:\n" << lightProj << endl;

        glMatrixMode(GL_MODELVIEW);
        glPushMatrix();
        glLoadIdentity();

        mShadowCam->SetupCameraView();


        //////////////
        //-- compute texture matrix
        static Matrix4x4 biasMatrix(0.5f, 0.0f, 0.0f, 0.5f,
                                                                0.0f, 0.5f, 0.0f, 0.5f,
                                                                0.0f, 0.0f, 0.5f, 0.5f,
                                                                0.0f, 0.0f, 0.0f, 1.0f);

        mTextureMatrix = mLightProjView * biasMatrix; 




        /////////////
        //-- render scene into shadow map

        renderer->RenderScene();

        
        glDisable(GL_POLYGON_OFFSET_FILL);
        glMatrixMode(GL_MODELVIEW);
        glPopMatrix();

        glMatrixMode(GL_PROJECTION);
        glPopMatrix();

        glPopAttrib();
#if 0
        float *data = new float[mSize * mSize];

        GrabDepthBuffer(data, mFbo->GetDepthTex());
        ExportDepthBuffer(data, mSize);

        delete [] data;
        
        PrintGLerror("shadow map");
#endif
        FrameBufferObject::Release();
}


void ShadowMap::GetTextureMatrix(Matrix4x4 &m) const
{
        m = mTextureMatrix;
}

 
unsigned int ShadowMap::GetShadowTexture() const
{
        return mFbo->GetDepthTex();
}



} // namespace