source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/SceneQuery.cpp @ 2892

#include "SceneQuery.h"
#include "glInterface.h"
#include "Vector3.h"
#include "Camera.h"
#include "SceneQuery.h"
#include "RenderTraverser.h"
#include "FrameBufferObject.h"

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




using namespace std;

const static int texWidth = 2048;
const static int texHeight = 2048;


static GLenum mrt[] = {GL_COLOR_ATTACHMENT0_EXT, GL_COLOR_ATTACHMENT1_EXT, GL_COLOR_ATTACHMENT2_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 void startil()
{
        ilInit();
        assert(ilGetError() == IL_NO_ERROR);
}


static void stopil()
{
        ilShutDown();
        assert(ilGetError() == IL_NO_ERROR);
}


namespace CHCDemoEngine
{


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)
{
        startil();

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

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

        if (!ilTexImage(texWidth, texHeight, depth, bpp, IL_LUMINANCE, IL_FLOAT, data))
        {
                cerr << "IL error " << ilGetError() << endl;
                stopil();
                return;
        }

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

        stopil();

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


SceneQuery::SceneQuery(const AxisAlignedBox3 &sceneBox, 
                                           RenderTraverser *renderer): 
mSceneBox(sceneBox), mDepth(NULL)
{
        Prepare(renderer);
}


bool SceneQuery::CalcIntersection(Vector3 &pt)
{
        const int px = (mSceneBox.Max(0) - pt.x) * (texWidth - 1) / mSceneBox.Size(0);
        const int py = (mSceneBox.Max(1) - pt.y) * (texHeight - 1) / mSceneBox.Size(1);

        float d = mDepth[px + py * texHeight];

        static float depth = d;

        if (d > 0)
        {
                // temporal smoothing of depth values
                const float x = .5f;
                depth = d * x + depth * (1.0f - x);

                const float offs = mSceneBox.Size(2) * 5e-2f;
                pt.z =  mSceneBox.Max().z - mSceneBox.Size().z * depth + offs;

                return true;
        }

        return false;
}


void SceneQuery::Prepare(RenderTraverser *renderer)
{
        cout << "Preparing scene queries" << endl;

        const float xlen = mSceneBox.Size().x * 0.5f;
        const float ylen = mSceneBox.Size().y * 0.5f;
        
        Camera *orthoCam = new Camera(xlen, ylen);
        orthoCam->SetOrtho(true);

        orthoCam->SetNear(0.0f);
        orthoCam->SetDirection(Vector3(0, 0, -1));

        Vector3 pos = Vector3(mSceneBox.Center().x, mSceneBox.Center().y, mSceneBox.Max().z);
        orthoCam->SetPosition(pos);

        FrameBufferObject *fbo = new FrameBufferObject(texWidth, texHeight, FrameBufferObject::DEPTH_32, true);
        fbo->AddColorBuffer(ColorBufferObject::BUFFER_UBYTE, ColorBufferObject::WRAP_CLAMP_TO_EDGE, ColorBufferObject::FILTER_NEAREST, false);


        fbo->Bind();

        glDrawBuffers(1, mrt);

        glPushAttrib(GL_VIEWPORT_BIT);
        glViewport(0, 0, texWidth, texHeight);

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        glFrontFace(GL_CCW);
        glCullFace(GL_BACK);
        
        glEnable(GL_CULL_FACE);

        glShadeModel(GL_FLAT);
        glEnable(GL_DEPTH_TEST);

        glMatrixMode(GL_PROJECTION);
        glPushMatrix();

        glOrtho(+xlen, -xlen, ylen, -ylen, 0.0f, mSceneBox.Size().z); 

        glMatrixMode(GL_MODELVIEW);
        glPushMatrix();

        orthoCam->SetupCameraView();

        mDepth = new float[texHeight * texWidth];

        renderer->RenderScene();
        
        glPopMatrix();
        glMatrixMode(GL_PROJECTION);
        
        glPopMatrix();

        glPopAttrib();
        
        FrameBufferObject::Release();

        GrabDepthBuffer(mDepth, fbo->GetDepthTex());
        //ExportDepthBuffer(mDepth); PrintGLerror("grab");

        DEL_PTR(fbo);
        DEL_PTR(orthoCam);
}




}