src/utils/SkCamera.cpp

/* libs/graphics/effects/SkCamera.cpp
**
** Copyright 2006, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License"); 
** you may not use this file except in compliance with the License. 
** You may obtain a copy of the License at 
**
**     http://www.apache.org/licenses/LICENSE-2.0 
**
** Unless required by applicable law or agreed to in writing, software 
** distributed under the License is distributed on an "AS IS" BASIS, 
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
** See the License for the specific language governing permissions and 
** limitations under the License.
*/

#include "SkCamera.h"

static SkScalar SkScalarDotDiv(int count, const SkScalar a[], int step_a,
                               const SkScalar b[], int step_b,
                               SkScalar denom)
{
#ifdef SK_SCALAR_IS_FLOAT
    float prod = 0;
    for (int i = 0; i < count; i++)
    {
        prod += a[0] * b[0];
        a += step_a;
        b += step_b;
    }
    return prod / denom;
#else
    Sk64    prod, tmp;

    prod.set(0);
    for (int i = 0; i < count; i++)
    {
        tmp.setMul(a[0], b[0]);
        prod.add(tmp);
        a += step_a;
        b += step_b;
    }
    prod.div(denom, Sk64::kRound_DivOption);
    return prod.get32();
#endif
}

static SkScalar SkScalarDot(int count, const SkScalar a[], int step_a,
                                       const SkScalar b[], int step_b)
{
#ifdef SK_SCALAR_IS_FLOAT
    float prod = 0;
    for (int i = 0; i < count; i++)
    {
        prod += a[0] * b[0];
        a += step_a;
        b += step_b;
    }
    return prod;
#else
    Sk64    prod, tmp;

    prod.set(0);
    for (int i = 0; i < count; i++)
    {
        tmp.setMul(a[0], b[0]);
        prod.add(tmp);
        a += step_a;
        b += step_b;
    }
    return prod.getFixed();
#endif
}

//////////////////////////////////////////////////////////////////////////

SkUnitScalar SkPoint3D::normalize(SkUnit3D* unit) const
{
#ifdef SK_SCALAR_IS_FLOAT
    float mag = sk_float_sqrt(fX*fX + fY*fY + fZ*fZ);
    if (mag)
    {
        float scale = 1.0f / mag;
        unit->fX = fX * scale;
        unit->fY = fY * scale;
        unit->fZ = fZ * scale;
    }
#else
    Sk64    tmp1, tmp2;

    tmp1.setMul(fX, fX);
    tmp2.setMul(fY, fY);
    tmp1.add(tmp2);
    tmp2.setMul(fZ, fZ);
    tmp1.add(tmp2);

    SkFixed mag = tmp1.getSqrt();
    if (mag)
    {
        // what if mag < SK_Fixed1 ??? we will underflow the fixdiv
        SkFixed scale = SkFixedDiv(SK_Fract1, mag);
        unit->fX = SkFixedMul(fX, scale);
        unit->fY = SkFixedMul(fY, scale);
        unit->fZ = SkFixedMul(fZ, scale);
    }
#endif
    return mag;
}

SkUnitScalar SkUnit3D::Dot(const SkUnit3D& a, const SkUnit3D& b)
{
    return  SkUnitScalarMul(a.fX, b.fX) +
            SkUnitScalarMul(a.fY, b.fY) +
            SkUnitScalarMul(a.fZ, b.fZ);
}

void SkUnit3D::Cross(const SkUnit3D& a, const SkUnit3D& b, SkUnit3D* cross)
{
    SkASSERT(cross);

    // use x,y,z, in case &a == cross or &b == cross


    SkScalar x = SkUnitScalarMul(a.fY, b.fZ) - SkUnitScalarMul(a.fZ, b.fY);
    SkScalar y = SkUnitScalarMul(a.fZ, b.fX) - SkUnitScalarMul(a.fX, b.fY);
    SkScalar z = SkUnitScalarMul(a.fX, b.fY) - SkUnitScalarMul(a.fY, b.fX);

    cross->set(x, y, z);
}

///////////////////////////////////////////////////////////////////////////

SkPatch3D::SkPatch3D()
{
    this->reset();
}

void SkPatch3D::reset()
{
    fOrigin.set(0, 0, 0);
    fU.set(SK_Scalar1, 0, 0);
    fV.set(0, -SK_Scalar1, 0);
}

void SkPatch3D::transform(const SkMatrix3D& m, SkPatch3D* dst) const
{
    if (dst == NULL)
        dst = (SkPatch3D*)this;

    m.mapVector(fU, &dst->fU);
    m.mapVector(fV, &dst->fV);
    m.mapPoint(fOrigin, &dst->fOrigin);
}

SkScalar SkPatch3D::dotWith(SkScalar dx, SkScalar dy, SkScalar dz) const
{
    SkScalar cx = SkScalarMul(fU.fY, fV.fZ) - SkScalarMul(fU.fZ, fV.fY);
    SkScalar cy = SkScalarMul(fU.fZ, fV.fX) - SkScalarMul(fU.fX, fV.fY);
    SkScalar cz = SkScalarMul(fU.fX, fV.fY) - SkScalarMul(fU.fY, fV.fX);

    return SkScalarMul(cx, dx) + SkScalarMul(cy, dy) + SkScalarMul(cz, dz);
}

///////////////////////////////////////////////////////////////////////////

void SkMatrix3D::reset()
{
    memset(fMat, 0, sizeof(fMat));
    fMat[0][0] = fMat[1][1] = fMat[2][2] = SK_Scalar1;
}

void SkMatrix3D::setTranslate(SkScalar x, SkScalar y, SkScalar z)
{
    memset(fMat, 0, sizeof(fMat));
    fMat[0][0] = x;
    fMat[1][1] = y;
    fMat[2][2] = z;
}

void SkMatrix3D::setRotateX(SkScalar degX)
{
    SkScalar    s, c;

    s = SkScalarSinCos(SkDegreesToRadians(degX), &c);
    this->setRow(0, SK_Scalar1, 0, 0);
    this->setRow(1, 0, c, -s);
    this->setRow(2, 0, s, c);
}

void SkMatrix3D::setRotateY(SkScalar degY)
{
    SkScalar    s, c;

    s = SkScalarSinCos(SkDegreesToRadians(degY), &c);
    this->setRow(0, c, 0, -s);
    this->setRow(1, 0, SK_Scalar1, 0);
    this->setRow(2, s, 0, c);
}

void SkMatrix3D::setRotateZ(SkScalar degZ)
{
    SkScalar    s, c;

    s = SkScalarSinCos(SkDegreesToRadians(degZ), &c);
    this->setRow(0, c, -s, 0);
    this->setRow(1, s, c, 0);
    this->setRow(2, 0, 0, SK_Scalar1);
}

void SkMatrix3D::preTranslate(SkScalar x, SkScalar y, SkScalar z)
{
    SkScalar col[3] = { x, y, z};

    for (int i = 0; i < 3; i++)
        fMat[i][3] += SkScalarDot(3, &fMat[i][0], 1, col, 1);
}

void SkMatrix3D::preRotateX(SkScalar degX)
{
    SkMatrix3D m;    
    m.setRotateX(degX);
    this->setConcat(*this, m);
}

void SkMatrix3D::preRotateY(SkScalar degY)
{
    SkMatrix3D m;    
    m.setRotateY(degY);
    this->setConcat(*this, m);
}

void SkMatrix3D::preRotateZ(SkScalar degZ)
{
    SkMatrix3D m;    
    m.setRotateZ(degZ);
    this->setConcat(*this, m);
}

void SkMatrix3D::setConcat(const SkMatrix3D& a, const SkMatrix3D& b)
{
    SkMatrix3D  tmp;
    SkMatrix3D* c = this;

    if (this == &a || this == &b)
        c = &tmp;

    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++)
            c->fMat[i][j] = SkScalarDot(3, &a.fMat[i][0], 1, &b.fMat[0][j], 4);
        c->fMat[i][3] = SkScalarDot(3, &a.fMat[i][0], 1, &b.fMat[0][3], 4) + a.fMat[i][3];
    }

    if (c == &tmp)
        *this = tmp;
}

void SkMatrix3D::mapPoint(const SkPoint3D& src, SkPoint3D* dst) const
{
    SkScalar x = SkScalarDot(3, &fMat[0][0], 1, &src.fX, 1) + fMat[0][3];
    SkScalar y = SkScalarDot(3, &fMat[1][0], 1, &src.fX, 1) + fMat[1][3];
    SkScalar z = SkScalarDot(3, &fMat[2][0], 1, &src.fX, 1) + fMat[2][3];
    dst->set(x, y, z);
}

void SkMatrix3D::mapVector(const SkVector3D& src, SkVector3D* dst) const
{
    SkScalar x = SkScalarDot(3, &fMat[0][0], 1, &src.fX, 1);
    SkScalar y = SkScalarDot(3, &fMat[1][0], 1, &src.fX, 1);
    SkScalar z = SkScalarDot(3, &fMat[2][0], 1, &src.fX, 1);
    dst->set(x, y, z);
}

///////////////////////////////////////////////////////////////////////////

SkCamera3D::SkCamera3D()
{
    this->reset();
}

void SkCamera3D::reset()
{
    fLocation.set(0, 0, -SkIntToScalar(576));   // 8 inches backward
    fAxis.set(0, 0, SK_Scalar1);                // forward
    fZenith.set(0, -SK_Scalar1, 0);             // up

    fObserver.set(0, 0, fLocation.fZ);

    fNeedToUpdate = true;
}

void SkCamera3D::update()
{
    fNeedToUpdate = true;
}

void SkCamera3D::doUpdate() const
{
    SkUnit3D    axis, zenith, cross;

    fAxis.normalize(&axis);

    {
        SkScalar dot = SkUnit3D::Dot(*(const SkUnit3D*)(const void*)&fZenith, axis);

        zenith.fX = fZenith.fX - SkUnitScalarMul(dot, axis.fX);
        zenith.fY = fZenith.fY - SkUnitScalarMul(dot, axis.fY);
        zenith.fZ = fZenith.fZ - SkUnitScalarMul(dot, axis.fZ);

        (void)((SkPoint3D*)(void*)&zenith)->normalize(&zenith);
    }

    SkUnit3D::Cross(axis, zenith, &cross);

    {
        SkMatrix* orien = &fOrientation;
        SkScalar x = fObserver.fX;
        SkScalar y = fObserver.fY;
        SkScalar z = fObserver.fZ;

        orien->set(SkMatrix::kMScaleX, SkUnitScalarMul(x, axis.fX) - SkUnitScalarMul(z, cross.fX));
        orien->set(SkMatrix::kMSkewX,  SkUnitScalarMul(x, axis.fY) - SkUnitScalarMul(z, cross.fY));
        orien->set(SkMatrix::kMTransX, SkUnitScalarMul(x, axis.fZ) - SkUnitScalarMul(z, cross.fZ));
        orien->set(SkMatrix::kMSkewY,  SkUnitScalarMul(y, axis.fX) - SkUnitScalarMul(z, zenith.fX));
        orien->set(SkMatrix::kMScaleY, SkUnitScalarMul(y, axis.fY) - SkUnitScalarMul(z, zenith.fY));
        orien->set(SkMatrix::kMTransY, SkUnitScalarMul(y, axis.fZ) - SkUnitScalarMul(z, zenith.fZ));
        orien->set(SkMatrix::kMPersp0, axis.fX);
        orien->set(SkMatrix::kMPersp1, axis.fY);
        orien->set(SkMatrix::kMPersp2, axis.fZ);
    }
}

void SkCamera3D::patchToMatrix(const SkPatch3D& quilt, SkMatrix* matrix) const
{
    if (fNeedToUpdate)
    {
        this->doUpdate();
        fNeedToUpdate = false;
    }

    const SkScalar* mapPtr = (const SkScalar*)(const void*)&fOrientation;
    const SkScalar* patchPtr;
    SkPoint3D       diff;
    SkScalar        dot;

    diff.fX = quilt.fOrigin.fX - fLocation.fX;
    diff.fY = quilt.fOrigin.fY - fLocation.fY;
    diff.fZ = quilt.fOrigin.fZ - fLocation.fZ;

    dot = SkUnit3D::Dot(*(const SkUnit3D*)(const void*)&diff,
                        *(const SkUnit3D*)(((const SkScalar*)(const void*)&fOrientation) + 6));

    patchPtr = (const SkScalar*)&quilt;
    matrix->set(SkMatrix::kMScaleX, SkScalarDotDiv(3, patchPtr, 1, mapPtr, 1, dot));
    matrix->set(SkMatrix::kMSkewY,  SkScalarDotDiv(3, patchPtr, 1, mapPtr+3, 1, dot));
    matrix->set(SkMatrix::kMPersp0, SkScalarDotDiv(3, patchPtr, 1, mapPtr+6, 1, dot));

    patchPtr += 3;
    matrix->set(SkMatrix::kMSkewX,  SkScalarDotDiv(3, patchPtr, 1, mapPtr, 1, dot));
    matrix->set(SkMatrix::kMScaleY, SkScalarDotDiv(3, patchPtr, 1, mapPtr+3, 1, dot));
    matrix->set(SkMatrix::kMPersp1, SkScalarDotDiv(3, patchPtr, 1, mapPtr+6, 1, dot));

    patchPtr = (const SkScalar*)(const void*)&diff;
    matrix->set(SkMatrix::kMTransX, SkScalarDotDiv(3, patchPtr, 1, mapPtr, 1, dot));
    matrix->set(SkMatrix::kMTransY, SkScalarDotDiv(3, patchPtr, 1, mapPtr+3, 1, dot));
    matrix->set(SkMatrix::kMPersp2, SK_UnitScalar1);
}

///////////////////////////////////////////////////////////////////////////////////////////////////

Sk3DView::Sk3DView()
{
    fInitialRec.fMatrix.reset();
    fRec = &fInitialRec;
}

Sk3DView::~Sk3DView()
{
    Rec* rec = fRec;
    while (rec != &fInitialRec) {
        Rec* next = rec->fNext;
        SkDELETE(rec);
        rec = next;
    }
}

void Sk3DView::save()
{
    Rec* rec = SkNEW(Rec);
    rec->fNext = fRec;
    rec->fMatrix = fRec->fMatrix;
    fRec = rec;
}

void Sk3DView::restore()
{
    SkASSERT(fRec != &fInitialRec);
    Rec* next = fRec->fNext;
    SkDELETE(fRec);
    fRec = next;
}

void Sk3DView::translate(SkScalar x, SkScalar y, SkScalar z)
{
    fRec->fMatrix.preTranslate(x, y, z);
}

void Sk3DView::rotateX(SkScalar deg)
{
    fRec->fMatrix.preRotateX(deg);
}

void Sk3DView::rotateY(SkScalar deg)
{
    fRec->fMatrix.preRotateY(deg);
}

void Sk3DView::rotateZ(SkScalar deg)
{
    fRec->fMatrix.preRotateZ(deg);
}

SkScalar Sk3DView::dotWithNormal(SkScalar x, SkScalar y, SkScalar z) const
{
    SkPatch3D   patch;
    patch.transform(fRec->fMatrix);
    return patch.dotWith(x, y, z);
}

void Sk3DView::getMatrix(SkMatrix* matrix) const
{
    if (matrix != NULL)
    {
        SkPatch3D   patch;
        patch.transform(fRec->fMatrix);
        fCamera.patchToMatrix(patch, matrix);
    }
}

#include "SkCanvas.h"

void Sk3DView::applyToCanvas(SkCanvas* canvas) const
{
    SkMatrix    matrix;
    
    this->getMatrix(&matrix);
    canvas->concat(matrix);
}