source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/SkyPreetham.cpp @ 2983

#include "SkyPreetham.h"
#include "common.h"
#include "Vector3.h"
#include "SceneEntity.h"
#include "Transform3.h"
#include "Camera.h"
#include "RenderState.h"

using namespace CHCDemoEngine;
using namespace std;



static CGprogram sCgSkyProgram = NULL;
static CGprogram sCgMrtFragmentSkyDomeProgram = NULL;


static CGparameter sLightDirParam;
static CGparameter sThetaSunParam;
static CGparameter sZenithColorParam;
static CGparameter sAColorParam;
static CGparameter sBColorParam;
static CGparameter sCColorParam;
static CGparameter sDColorParam;
static CGparameter sEColorParam;
static CGparameter sMultiplierParam;



inline float CBQ(float x)
{
        return x * x * x;
}


inline float SQR(float x)
{
        return x * x ;
}


void SkyPreetham::Init(CGcontext context)
{       
        sCgSkyProgram = 
                cgCreateProgramFromFile(context, 
                                                                CG_SOURCE,
                                                                "src/shaders/sky_preetham.cg", 
                                                                RenderState::sCgVertexProfile,
                                                                "default_vs",
                                                                NULL);

        if (sCgSkyProgram != NULL)
        {
                cgGLLoadProgram(sCgSkyProgram);

                sLightDirParam = cgGetNamedParameter(sCgSkyProgram, "lightDir");
                sThetaSunParam = cgGetNamedParameter(sCgSkyProgram, "thetaSun");
                sZenithColorParam = cgGetNamedParameter(sCgSkyProgram, "zenithColor");
                sAColorParam = cgGetNamedParameter(sCgSkyProgram, "aColor");
                sBColorParam = cgGetNamedParameter(sCgSkyProgram, "bColor");
                sCColorParam = cgGetNamedParameter(sCgSkyProgram, "cColor");
                sDColorParam = cgGetNamedParameter(sCgSkyProgram, "dColor");
                sEColorParam = cgGetNamedParameter(sCgSkyProgram, "eColor");

                sMultiplierParam = cgGetNamedParameter(sCgSkyProgram, "multiplier");
        }
        else
                cerr << "sky program failed to load" << endl;

        sCgMrtFragmentSkyDomeProgram = 
                cgCreateProgramFromFile(context, 
                                                                CG_SOURCE,
                                                                "src/shaders/sky_preetham.cg", 
                                                                RenderState::sCgFragmentProfile,
                                                                "frag_skydome",
                                                                NULL);

        if (sCgMrtFragmentSkyDomeProgram != NULL)
        {
                cgGLLoadProgram(sCgMrtFragmentSkyDomeProgram);
                //cgGLSetParameter1f(sMaxDepthParam, MAX_DEPTH_CONST / farDist);
        }
        else
                cerr << "fragment skyprogram failed to load" << endl;
}


SkyPreetham::SkyPreetham(float turbitity, SceneEntity *skyDome):
mSkyDome(skyDome),
mTurbidity(turbitity)
//, mSunQuad(NULL)
{
        CreateSunQuad();
}


SkyPreetham::~SkyPreetham()
{
        //DEL_PTR(mSunQuad);
}


void SkyPreetham::RenderSkyDome(const Vector3 &sunDir, 
                                                                Camera *camera, 
                                                                RenderState *state, 
                                                                bool scaleToRange)
{
        pair<float, float> sun_theta;
        Vector3 zenithColor;
        vector<Vector3> ABCDE;
        ComputeFactors(sunDir, zenithColor, ABCDE, sun_theta);

        // Move skybox with camera.
        Vector3 position = camera->GetPosition();

        const float scaleFactor = 80.0f;
        //const float scaleFactor = 5.0f;

        position.z -= 3 * scaleFactor;
        Matrix4x4 m = TranslationMatrix(position);

        Matrix4x4 s = ScaleMatrix(scaleFactor, scaleFactor, scaleFactor);
        mSkyDome->GetTransform()->SetMatrix(s * m);
        
        cgGLSetParameter3f(sLightDirParam, sunDir.x, sunDir.y, sunDir.z);
        cgGLSetParameter2f(sThetaSunParam, sun_theta.first, sun_theta.second);
        cgGLSetParameter3f(sZenithColorParam, zenithColor.x, zenithColor.y, zenithColor.z);

        cgGLSetParameter3f(sAColorParam, ABCDE[0].x, ABCDE[0].y, ABCDE[0].z);
        cgGLSetParameter3f(sBColorParam, ABCDE[1].x, ABCDE[1].y, ABCDE[1].z);
        cgGLSetParameter3f(sCColorParam, ABCDE[2].x, ABCDE[2].y, ABCDE[2].z);
        cgGLSetParameter3f(sDColorParam, ABCDE[3].x, ABCDE[3].y, ABCDE[3].z);
        cgGLSetParameter3f(sEColorParam, ABCDE[4].x, ABCDE[4].y, ABCDE[4].z);

        if (state->GetRenderPassType() == RenderState::DEFERRED)
        {
                cgGLEnableProfile(RenderState::sCgFragmentProfile);
                cgGLBindProgram(sCgMrtFragmentSkyDomeProgram);

        }

        if (!scaleToRange)
        {       
                // use tone mapping
                cgGLSetParameter1f(sMultiplierParam, 1.0f);
        }
        else
        {
                // no tone mapping => scale
                cgGLSetParameter1f(sMultiplierParam, 8e-5f);
        }

        cgGLEnableProfile(RenderState::sCgVertexProfile);
        cgGLBindProgram(sCgSkyProgram);

        // Render sky dome.
        mSkyDome->Render(state);

        // Render additively blended sun disc.
        //RenderSunDisk(sunDir, camera);

        cgGLDisableProfile(RenderState::sCgFragmentProfile);
}


void SkyPreetham::RenderSunDisk(const Vector3 &sunDir, Camera *camera)
{
        // Move skybox with camera.
        Vector3 position = camera->GetPosition();

        const float scaleFactor = 100.0f;
        position.z -= 10 * scaleFactor;

        // Set world matrix to sun disc position.
        Matrix4x4 sunPos = TranslationMatrix(position);

        Vector3 ndir = -Normalize(sunDir);

        const float pitch = -atan2(ndir.x, ndir.y);
        const float yaw = atan2(ndir.z, sqrt((ndir.x * ndir.x) + (ndir.y * ndir.y)));

        Matrix4x4 roty = RotationYMatrix(pitch);
        Matrix4x4 rotx = RotationXMatrix(yaw);

        sunPos *= roty;
        sunPos *= rotx;;

        //sunposition.rotateAroundY(-D().getScene().getLight().getHorizontalOrientation() + 90.0f);
        //sunposition.rotateAroundX(-D().getScene().getLight().getVerticalOrientation());
        
        glMatrixMode(GL_MODELVIEW);
        glMultMatrixf((float *)sunPos.x);

        float ambient[] = {1.0f, 1.0f, 1.0f, 1.0f};

        glMaterialfv(GL_FRONT, GL_AMBIENT, ambient);

        //Float size = 0.5f + (1.0f - lightdirection.y) * 0.5f;

        //mSunEffect->setVariableVector3("LightDiffuseColor", D().getScene().getLight().getDiffuseColor());
        //mSunEffect->setVariableFloat("SunSize", size);
        //mSunEffect->setVariableTexture2D("SunTexture", mSunTexture);

        /*mSunEffect->activate();
        
        mSunQuad->render();

        mSunEffect->deactivate();
        F().getRenderDevice().setDefaultBlendingMode(FRenderDevice::BLENDING_NONE);*/

        glPopMatrix();
}


void SkyPreetham::CreateSunQuad()
{
        /*
        mSunQuad = new FVertexBuffer();
        mSunQuad->setupPrimitiveType(FVertexBuffer::PRIMITIVES_TRIANGLES);
        mSunQuad->setupVertexFormat(3, 0, 0, true);
        mSunQuad->setupTexCoordSet(0, 2);
        mSunQuad->setVertexBufferSize(4, 6);

        mSunQuad->setVertexPosition(0, FVector3(-0.1f,  0.1f, 1.0f));
        mSunQuad->setVertexPosition(1, FVector3( 0.1f,  0.1f, 1.0f));
        mSunQuad->setVertexPosition(2, FVector3(-0.1f, -0.1f, 1.0f));
        mSunQuad->setVertexPosition(3, FVector3( 0.1f, -0.1f, 1.0f));
        mSunQuad->setVertexTexCoord(0, 0, FVector2(0.0f, 0.0f));
        mSunQuad->setVertexTexCoord(1, 0, FVector2(1.0f, 0.0f));
        mSunQuad->setVertexTexCoord(2, 0, FVector2(0.0f, 1.0f));
        mSunQuad->setVertexTexCoord(3, 0, FVector2(1.0f, 1.0f));

        mSunQuad->setIndex(0, 0);
        mSunQuad->setIndex(1, 1);
        mSunQuad->setIndex(2, 2);
        mSunQuad->setIndex(3, 2);
        mSunQuad->setIndex(4, 1);
        mSunQuad->setIndex(5, 3);
        */
}


void SkyPreetham::ComputeFactors(const Vector3 &sunDir, 
                                                                 Vector3 &zenithColor, 
                                                                 vector<Vector3> &ABCDE,  
                                                                 std::pair<float, float> &sunThetha) const
{
        sunThetha.first = acos(sunDir.z);

        const float cos_theta = cos(sunThetha.first);
        sunThetha.second = cos_theta * cos_theta;

        zenithColor.x = ( 0.00165f * CBQ(sunThetha.first) - 0.00374f * SQR(sunThetha.first) + 0.00208f * sunThetha.first + 0.0f)     * SQR(mTurbidity) +        
                                    (-0.02902f * CBQ(sunThetha.first) + 0.06377f * SQR(sunThetha.first) - 0.03202f * sunThetha.first + 0.00394f) * mTurbidity +
                                        ( 0.11693f * CBQ(sunThetha.first) - 0.21196f * SQR(sunThetha.first) + 0.06052f * sunThetha.first + 0.25885f);

        zenithColor.y = ( 0.00275f * CBQ(sunThetha.first) - 0.00610f * SQR(sunThetha.first) + 0.00316f * sunThetha.first + 0.0f)     * SQR(mTurbidity) +
                        (-0.04214f * CBQ(sunThetha.first) + 0.08970f * SQR(sunThetha.first) - 0.04153f * sunThetha.first + 0.00515f) * mTurbidity +
                            ( 0.15346f * CBQ(sunThetha.first) - 0.26756f * SQR(sunThetha.first) + 0.06669f * sunThetha.first + 0.26688f);
        
        zenithColor.z  = (float)((4.0453f * mTurbidity - 4.9710f) *     tan((4.0f / 9.0f - mTurbidity / 120.0f) * 
                                                         (M_PI - 2.0f * sunThetha.first)) - 0.2155f * mTurbidity + 2.4192f);

        // convert kcd/m² to cd/m²
        zenithColor.z *= 1000.0f;

        ABCDE.push_back(Vector3(-0.01925 * mTurbidity - 0.25922, -0.01669 * mTurbidity - 0.26078,  0.17872 * mTurbidity - 1.46303));
        ABCDE.push_back(Vector3(-0.06651 * mTurbidity + 0.00081, -0.09495 * mTurbidity + 0.00921, -0.35540 * mTurbidity + 0.42749));
        ABCDE.push_back(Vector3(-0.00041 * mTurbidity + 0.21247, -0.00792 * mTurbidity + 0.21023, -0.02266 * mTurbidity + 5.32505));
        ABCDE.push_back(Vector3(-0.06409 * mTurbidity - 0.89887, -0.04405 * mTurbidity - 1.65369,  0.12064 * mTurbidity - 2.57705));
        ABCDE.push_back(Vector3(-0.00325 * mTurbidity + 0.04517, -0.01092 * mTurbidity + 0.05291, -0.06696 * mTurbidity + 0.37027));
}


void SkyPreetham::ComputeSunColor(const Vector3 &sunDir, 
                                                                  Vector3 &ambient, 
                                                                  Vector3 &diffuse,
                                                                  bool scaleToRange) const
{
        // sunDir is sun direction
        // ambient color: shadow color
        // diffuse color: sun color
        pair<float, float> sun_theta;
        Vector3 zenithColor;
        vector<Vector3> ABCDE;

        ComputeFactors(sunDir, zenithColor, ABCDE, sun_theta);

        Vector3 zenith_XYZ;                                                                                             

        zenith_XYZ.x = (zenithColor.x / zenithColor.y) * zenithColor.z;                                                                        
        zenith_XYZ.y = zenithColor.z;                                                                                          
        zenith_XYZ.z = ((1.0f - zenithColor.x - zenithColor.y) / zenithColor.y) * zenithColor.z;                                                                

        ambient.x =  3.240479f * zenith_XYZ.x - 1.537150f * zenith_XYZ.y - 0.498535f * zenith_XYZ.z;
        ambient.y = -0.969256f * zenith_XYZ.x + 1.875992f * zenith_XYZ.y + 0.041556f * zenith_XYZ.z;    
        ambient.z =  0.055648f * zenith_XYZ.x - 0.204043f * zenith_XYZ.y + 1.057311f * zenith_XYZ.z;

        // downscale ambient color
        if (scaleToRange)
                ambient *= 2e-5f;
        else
                ambient *= 1e-1f;

        // simulate the sun intensity by modulating the ambient term.
        ambient *= (10.0f - 9.0f * DotProd(sunDir, Vector3::UNIT_Z()));
        //ambient += Vector3(0.2f);

        Vector3 num;
          
        num.x = (1.0f + ABCDE[0].x * exp(ABCDE[1].x / sunDir.z)) * (1.0f + ABCDE[2].x)+ ABCDE[4].x;    
        num.y = (1.0f + ABCDE[0].y * exp(ABCDE[1].y / sunDir.z)) * (1.0f + ABCDE[2].y)+ ABCDE[4].y;   
        num.z = (1.0f + ABCDE[0].z * exp(ABCDE[1].z / sunDir.z)) * (1.0f + ABCDE[2].z)+ ABCDE[4].z;   

        Vector3 den;

        den.x = (1.0f + ABCDE[0].x * exp(ABCDE[1].x)) * (1.0f + ABCDE[2].x * exp(ABCDE[3].x * sun_theta.first) + ABCDE[4].x * sun_theta.second);  
        den.y = (1.0f + ABCDE[0].y * exp(ABCDE[1].y)) * (1.0f + ABCDE[2].y * exp(ABCDE[3].y * sun_theta.first) + ABCDE[4].y * sun_theta.second);   
        den.z = (1.0f + ABCDE[0].z * exp(ABCDE[1].z)) * (1.0f + ABCDE[2].z * exp(ABCDE[3].z * sun_theta.first) + ABCDE[4].z * sun_theta.second);   


        Vector3 xyY = zenithColor * num / den;    

        Vector3 XYZ;                                                                                             

        XYZ.x = (xyY.x / xyY.y) * xyY.z;                                                                        
        XYZ.y = xyY.z;                                                                                          
        XYZ.z = ((1.0f - xyY.x - xyY.y) / xyY.y) * xyY.z;                                                                


        /////////////
        //-- transform to rgb

        Vector3 color;  
        color.x =  3.240479f * XYZ.x - 1.537150f * XYZ.y - 0.498535f * XYZ.z;
        color.y = -0.969256f * XYZ.x + 1.875992f * XYZ.y + 0.041556f *XYZ.z;    
        color.z =  0.055648f * XYZ.x - 0.204043f * XYZ.y + 1.057311f * XYZ.z;

        // Calculate final sun diffuse color.
        if (scaleToRange)
                diffuse = color * 5e-2f;
        else
                diffuse = color * 3e-1f;

        diffuse *= (2.0f - 1.0f * DotProd(sunDir, Vector3::UNIT_Z()));

        //cout << "diffuse: " << Magnitude(diffuse) << " ambient: " << Magnitude(ambient) << endl;
}