CWE-ou-minkata/Sources/Plasma/PubUtilLib/plGLight/plShadowSlave.cpp

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*==LICENSE==*/

#include "HeadSpin.h"

#include "plShadowSlave.h"
#include "plTweak.h"

#include <float.h>
#include <math.h>

#ifdef _MSC_VER
#define isnan _isnan
#endif

static const float kMinMinZ = 1.f; // totally random arbitrary number (has to be > 0).

bool plShadowSlave::ISetupOrthoViewTransform()
{
    hsBounds3Ext bnd = fCasterWorldBounds;

    bnd.Transform(&fWorldToLight);

    float minZ = bnd.GetMins().fZ;
    float maxZ = bnd.GetCenter().fZ + fAttenDist;

    float minX = bnd.GetMins().fX;
    float maxX = bnd.GetMaxs().fX;

    float minY = bnd.GetMins().fY;
    float maxY = bnd.GetMaxs().fY;


    hsMatrix44 proj;
    proj.Reset();
    proj.NotIdentity();

    // First the LightToTexture, which uses the above pretty much as is.
    // Note the remapping to range [0.5..width-0.5] etc. 
    // About this kAdjustBias. According to the docs, it should be 0.5,
    // and on the perspective projection 0.5 works great. But on the
    // directional (ortho) projection, it just makes the mapping wrong,
    // and an offset of zero works great. This could be a driver bug, or
    // hardware "dependency" (read IHV bug), but whatever, zero is working
    // now. Might need to adjust for new drivers or other hardware.
    const float kAdjustBias = 0.0f;
    proj.fMap[0][0] = 1.f / (maxX - minX);
    proj.fMap[0][3] = -minX / (maxX - minX) + kAdjustBias / fWidth;
    proj.fMap[1][1] = -1.f / (maxY - minY);
    proj.fMap[1][3] = -minY / (maxY - minY) + kAdjustBias / fHeight;
    proj.fMap[2][2] = 1.f;
    proj.fMap[3][3] = 1.f;

    fWorldToTexture = proj * fWorldToLight;

    // Now the LightToNDC. This one's a little trickier, because we want to compensate for
    // having brought in the viewport to keep our border constant, so we can clamp the 
    // projected texture and not have the edges smear off to infinity.
    // Like the adjust bias above, this part is correct in theory, but only
    // screws things up (increases Z-acne).
#if 0
    float delX = maxX - minX;
    minX += delX / (fWidth * 0.5f);
    maxX -= delX / (fWidth * 0.5f);
    float delY = maxY - minY;
    minY += delY / (fHeight * 0.5f);
    maxY -= delY / (fHeight * 0.5f);
#endif 


    fView.SetView(hsPoint3(minX, minY, minZ), hsPoint3(maxX, maxY, maxZ));
    fView.SetScreenSize((uint16_t)fWidth, (uint16_t)fHeight);
    fView.SetCameraTransform(fWorldToLight, fLightToWorld);
    fView.SetPerspective(false);
    fView.SetViewPort(0, 0, float(fWidth), float(fHeight), false);

    fLightDir = fLightToWorld.GetAxis(hsMatrix44::kUp);
    SetFlag(kPositional, false);
    SetFlag(kReverseCull, true);
    
    return true;
}

bool plShadowSlave::ISetupPerspViewTransform()
{
    hsBounds3Ext bnd = fCasterWorldBounds;

    bnd.Transform(&fWorldToLight);

    float minZ = bnd.GetMins().fZ;
    float maxZ = bnd.GetCenter().fZ + fAttenDist;

    if( minZ < kMinMinZ )
        minZ = kMinMinZ;

    // EAP
    // This is my hack to get the Nexus age working.  The real problem
    // is probably data-side.  I take full responsibility for this
    // hack-around breaking the entire system, loosing data, causing
    // unauthorized credit card transactions, etc.      
    if (isnan(bnd.GetMins().fX) || isnan(bnd.GetMins().fY))
        return false;
    if (isnan(bnd.GetMaxs().fX) || isnan(bnd.GetMaxs().fY))
        return false;

    float cotX, cotY;
    if( -bnd.GetMins().fX > bnd.GetMaxs().fX )
    {
        hsAssert(bnd.GetMins().fX < 0, "Empty shadow caster bounds?");
        cotX = -minZ / bnd.GetMins().fX;
    }
    else
    {
        hsAssert(bnd.GetMaxs().fX > 0, "Empty shadow caster bounds?");
        cotX = minZ / bnd.GetMaxs().fX;
    }

    if( -bnd.GetMins().fY > bnd.GetMaxs().fY )
    {
        hsAssert(bnd.GetMins().fY < 0, "Empty shadow caster bounds?");
        cotY = -minZ / bnd.GetMins().fY;
    }
    else
    {
        hsAssert(bnd.GetMaxs().fY > 0, "Empty shadow caster bounds?");
        cotY = minZ / bnd.GetMaxs().fY;
    }

    hsMatrix44 proj;
    proj.Reset();
    proj.NotIdentity();

    // First the LightToTexture, which uses the above pretty much as is.
    // Note the remapping to range [0.5..width-0.5] etc. Also, the perspective
    // divide is by the 3rd output (not the fourth), so we make the 3rd
    // output be W (instead of Z).
    // This also means that our translate goes into [i][2] instead of [i][3].
#if 0
    proj.fMap[0][0] = cotX * 0.5f;
    proj.fMap[0][2] = -0.5f * (1.f + 0.5f/fWidth);
    proj.fMap[1][1] = cotY * 0.5f;
    proj.fMap[1][2] = -0.5f * (1.f + 0.5f/fHeight);
#else
    plConst(float) kBiasScale(1.f);
    plConst(float) kBiasTrans(1.f);
    proj.fMap[0][0] = cotX * 0.5f * ( float(fWidth-2.f) / float(fWidth) ) * kBiasScale;
    proj.fMap[0][2] = 0.5f * (1.f - kBiasTrans * 0.5f/fWidth);
    proj.fMap[1][1] = -cotY * 0.5f * ( float(fHeight-2.f) / float(fHeight) ) * kBiasScale;
    proj.fMap[1][2] = 0.5f * (1.f - kBiasTrans * 0.5f/fHeight);
#endif

#if 0 // This computes correct Z, but we really just want W in 3rd component. HACKFISH
    proj.fMap[2][2] = maxZ / (maxZ - minZ);
    proj.fMap[2][3] = -minZ * maxZ / (maxZ - minZ);
#elif 1
    proj.fMap[2][2] = 1.f;
    proj.fMap[2][3] = 0;
#endif
    proj.fMap[3][2] = 1.f;
    proj.fMap[3][3] = 0;

    fWorldToTexture = proj * fWorldToLight;

    // Now the LightToNDC. This one's a little trickier, because we want to compensate for
    // having brought in the viewport to keep our border constant, so we can clamp the 
    // projected texture and not have the edges smear off to infinity.
    cotX -= cotX / (fWidth * 0.5f);
    cotY -= cotY / (fHeight * 0.5f);

    float tanX = 1.f / cotX;
    float tanY = 1.f / cotY;
    fView.SetView(hsPoint3(-tanX, -tanY, minZ), hsPoint3(tanX, tanY, maxZ));
    fView.SetScreenSize((uint16_t)fWidth, (uint16_t)fHeight);
    fView.SetCameraTransform(fWorldToLight, fLightToWorld);
    fView.SetPerspective(true);
    fView.SetViewPort(0, 0, float(fWidth), float(fHeight), false);

    fLightPos = fLightToWorld.GetTranslate();
    SetFlag(kPositional, true);

    return true;
}