source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/ShadowMapping.cpp @ 2894

#include "ShadowMapping.h"
#include "FrameBufferObject.h"
#include "RenderState.h"
#include "RenderTraverser.h"
#include "Light.h"
#include <IL/il.h>
#include <assert.h>

using namespace std;


namespace CHCDemoEngine
{

static GLenum mrt[] = {GL_COLOR_ATTACHMENT0_EXT, GL_COLOR_ATTACHMENT1_EXT, GL_COLOR_ATTACHMENT2_EXT, GL_COLOR_ATTACHMENT3_EXT};

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(int size, const AxisAlignedBox3 &sceneBox, Camera *cam):
mSceneBox(sceneBox), mSize(size), mCamera(cam)
{
        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);
}



void ShadowMap::ComputeShadowMap(Light *light, RenderTraverser *traverser)
{
        mLight = light;

        const float xlen = Magnitude(mSceneBox.Diagonal() * 0.5f);
        const float ylen = Magnitude(mSceneBox.Diagonal() * 0.5f);
        
        mShadowCam->SetDirection(light->GetDirection());
        
        // set position so that we can see the whole scene
        Vector3 pos = mSceneBox.Center();

        pos -= light->GetDirection() * 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);

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

        glMatrixMode(GL_MODELVIEW);
        glPushMatrix();

        glLoadIdentity();

        // setup shadow camera
        mShadowCam->SetupCameraView();

        //////////////
        //-- compute texture matrix

        Matrix4x4 lightView, lightProj;

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

        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); //bias from [-1, 1] to [0, 1]

        Matrix4x4 lightProjView = lightView * lightProj;
        mTextureMatrix = lightProjView * biasMatrix; 


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

        traverser->RenderScene();
        
        glDisable(GL_POLYGON_OFFSET_FILL);
        glMatrixMode(GL_MODELVIEW);
        glPopMatrix();

        glMatrixMode(GL_PROJECTION);
        glPopMatrix();

        glPopAttrib();
        
        /*float *data = new float[mSize * mSize];

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

        delete [] data;
        */
        PrintGLerror("shadow map");

        FrameBufferObject::Release();
}


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

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


} // namespace