scanline.cpp

Android 一些工具

    if (size > 16) {
        x >>= (size - 16);
    } else if (size < 16) {
        x = ggl_expand(x, size, 16);
    }
    x += x >> 15;
    return x;
}

void blend_factor(context_t* c, pixel_t* r, 
        uint32_t factor, const pixel_t* src, const pixel_t* dst)
{
    switch (factor) {
        case GGL_ZERO:
            r->c[1] = 
            r->c[2] = 
            r->c[3] = 
            r->c[0] = 0;
            break;
        case GGL_ONE:
            r->c[1] = 
            r->c[2] = 
            r->c[3] = 
            r->c[0] = FIXED_ONE;
            break;
        case GGL_DST_COLOR:
            r->c[1] = blendfactor(dst->c[1], dst->s[1]);
            r->c[2] = blendfactor(dst->c[2], dst->s[2]);
            r->c[3] = blendfactor(dst->c[3], dst->s[3]);
            r->c[0] = blendfactor(dst->c[0], dst->s[0]);
            break;
        case GGL_SRC_COLOR:
            r->c[1] = blendfactor(src->c[1], src->s[1]);
            r->c[2] = blendfactor(src->c[2], src->s[2]);
            r->c[3] = blendfactor(src->c[3], src->s[3]);
            r->c[0] = blendfactor(src->c[0], src->s[0]);
            break;
        case GGL_ONE_MINUS_DST_COLOR:
            r->c[1] = FIXED_ONE - blendfactor(dst->c[1], dst->s[1]);
            r->c[2] = FIXED_ONE - blendfactor(dst->c[2], dst->s[2]);
            r->c[3] = FIXED_ONE - blendfactor(dst->c[3], dst->s[3]);
            r->c[0] = FIXED_ONE - blendfactor(dst->c[0], dst->s[0]);
            break;
        case GGL_ONE_MINUS_SRC_COLOR:
            r->c[1] = FIXED_ONE - blendfactor(src->c[1], src->s[1]);
            r->c[2] = FIXED_ONE - blendfactor(src->c[2], src->s[2]);
            r->c[3] = FIXED_ONE - blendfactor(src->c[3], src->s[3]);
            r->c[0] = FIXED_ONE - blendfactor(src->c[0], src->s[0]);
            break;
        case GGL_SRC_ALPHA:
            r->c[1] = 
            r->c[2] = 
            r->c[3] = 
            r->c[0] = blendfactor(src->c[0], src->s[0], FIXED_ONE);
            break;
        case GGL_ONE_MINUS_SRC_ALPHA:
            r->c[1] = 
            r->c[2] = 
            r->c[3] = 
            r->c[0] = FIXED_ONE - blendfactor(src->c[0], src->s[0], FIXED_ONE);
            break;
        case GGL_DST_ALPHA:
            r->c[1] = 
            r->c[2] = 
            r->c[3] = 
            r->c[0] = blendfactor(dst->c[0], dst->s[0], FIXED_ONE);
            break;
        case GGL_ONE_MINUS_DST_ALPHA:
            r->c[1] = 
            r->c[2] = 
            r->c[3] = 
            r->c[0] = FIXED_ONE - blendfactor(dst->c[0], dst->s[0], FIXED_ONE);
            break;
        case GGL_SRC_ALPHA_SATURATE:
            // XXX: GGL_SRC_ALPHA_SATURATE
            break;
    }
}

static GGLfixed wrapping(int32_t coord, uint32_t size, int tx_wrap)
{
    GGLfixed d;
    if (tx_wrap == GGL_REPEAT) {
        d = (uint32_t(coord)>>16) * size;
    } else if (tx_wrap == GGL_CLAMP) { // CLAMP_TO_EDGE semantics
        const GGLfixed clamp_min = FIXED_HALF;
        const GGLfixed clamp_max = (size << 16) - FIXED_HALF;
        if (coord < clamp_min)     coord = clamp_min;
        if (coord > clamp_max)     coord = clamp_max;
        d = coord;
    } else { // 1:1
        const GGLfixed clamp_min = 0;
        const GGLfixed clamp_max = (size << 16);
        if (coord < clamp_min)     coord = clamp_min;
        if (coord > clamp_max)     coord = clamp_max;
        d = coord;
    }
    return d;
}

static inline
GGLcolor ADJUST_COLOR_ITERATOR(GGLcolor v, GGLcolor dvdx, int len)
{
    const int32_t end = dvdx * (len-1) + v;
    if (end < 0)
        v -= end;
    v &= ~(v>>31);
    return v;
}

void scanline(context_t* c)
{
    const uint32_t enables = c->state.enables;
    const int xs = c->iterators.xl;
    const int x1 = c->iterators.xr;
	int xc = x1 - xs;
    const int16_t* covPtr = c->state.buffers.coverage + xs;

    // All iterated values are sampled at the pixel center

    // reset iterators for that scanline...
    GGLcolor r, g, b, a;
    iterators_t& ci = c->iterators;
    if (enables & GGL_ENABLE_SMOOTH) {
        r = (xs * c->shade.drdx) + ci.ydrdy;
        g = (xs * c->shade.dgdx) + ci.ydgdy;
        b = (xs * c->shade.dbdx) + ci.ydbdy;
        a = (xs * c->shade.dadx) + ci.ydady;
        r = ADJUST_COLOR_ITERATOR(r, c->shade.drdx, xc);
        g = ADJUST_COLOR_ITERATOR(g, c->shade.dgdx, xc);
        b = ADJUST_COLOR_ITERATOR(b, c->shade.dbdx, xc);
        a = ADJUST_COLOR_ITERATOR(a, c->shade.dadx, xc);
    } else {
        r = ci.ydrdy;
        g = ci.ydgdy;
        b = ci.ydbdy;
        a = ci.ydady;
    }

    // z iterators are 1.31
    GGLfixed z = (xs * c->shade.dzdx) + ci.ydzdy;
    GGLfixed f = (xs * c->shade.dfdx) + ci.ydfdy;

    struct {
        GGLfixed s, t;
    } tc[GGL_TEXTURE_UNIT_COUNT];
    if (enables & GGL_ENABLE_TMUS) {
        for (int i=0 ; i<GGL_TEXTURE_UNIT_COUNT ; ++i) {
            if (c->state.texture[i].enable) {
                texture_iterators_t& ti = c->state.texture[i].iterators;
                if (enables & GGL_ENABLE_W) {
                    tc[i].s = ti.ydsdy;
                    tc[i].t = ti.ydtdy;
                } else {
                    tc[i].s = (xs * ti.dsdx) + ti.ydsdy;
                    tc[i].t = (xs * ti.dtdx) + ti.ydtdy;
                }
            }
        }
    }

    pixel_t fragment;
    pixel_t texel;
    pixel_t fb;

	uint32_t x = xs;
	uint32_t y = c->iterators.y;

	while (xc--) {
    
        { // just a scope

		// read color (convert to 8 bits by keeping only the integer part)
        fragment.s[1] = fragment.s[2] =
        fragment.s[3] = fragment.s[0] = 8;
        fragment.c[1] = r >> (GGL_COLOR_BITS-8);
        fragment.c[2] = g >> (GGL_COLOR_BITS-8);
        fragment.c[3] = b >> (GGL_COLOR_BITS-8);
        fragment.c[0] = a >> (GGL_COLOR_BITS-8);

		// texturing
        if (enables & GGL_ENABLE_TMUS) {
            for (int i=0 ; i<GGL_TEXTURE_UNIT_COUNT ; ++i) {
                texture_t& tx = c->state.texture[i];
                if (!tx.enable)
                    continue;
                texture_iterators_t& ti = tx.iterators;
                int32_t u, v;

                // s-coordinate
                if (tx.s_coord != GGL_ONE_TO_ONE) {
                    const int w = tx.surface.width;
                    u = wrapping(tc[i].s, w, tx.s_wrap);
                    tc[i].s += ti.dsdx;
                } else {
                    u = (((tx.shade.is0>>16) + x)<<16) + FIXED_HALF;
                }

                // t-coordinate
                if (tx.t_coord != GGL_ONE_TO_ONE) {
                    const int h = tx.surface.height;
                    v = wrapping(tc[i].t, h, tx.t_wrap);
                    tc[i].t += ti.dtdx;
                } else {
                    v = (((tx.shade.it0>>16) + y)<<16) + FIXED_HALF;
                }

                // read texture
                if (tx.mag_filter == GGL_NEAREST &&
                    tx.min_filter == GGL_NEAREST)
                {
                    u >>= 16;
                    v >>= 16;
                    tx.surface.read(&tx.surface, c, u, v, &texel);
                } else {
                    const int w = tx.surface.width;
                    const int h = tx.surface.height;
                    u -= FIXED_HALF;
                    v -= FIXED_HALF;
                    int u0 = u >> 16;
                    int v0 = v >> 16;
                    int u1 = u0 + 1;
                    int v1 = v0 + 1;
                    if (tx.s_wrap == GGL_REPEAT) {
                        if (u0<0)  u0 += w;
                        if (u1<0)  u1 += w;
                        if (u0>=w) u0 -= w;
                        if (u1>=w) u1 -= w;
                    } else {
                        if (u0<0)  u0 = 0;
                        if (u1<0)  u1 = 0;
                        if (u0>=w) u0 = w-1;
                        if (u1>=w) u1 = w-1;
                    }
                    if (tx.t_wrap == GGL_REPEAT) {
                        if (v0<0)  v0 += h;
                        if (v1<0)  v1 += h;
                        if (v0>=h) v0 -= h;
                        if (v1>=h) v1 -= h;
                    } else {
                        if (v0<0)  v0 = 0;
                        if (v1<0)  v1 = 0;
                        if (v0>=h) v0 = h-1;
                        if (v1>=h) v1 = h-1;
                    }
                    pixel_t texels[4];
                    uint32_t mm[4];
                    tx.surface.read(&tx.surface, c, u0, v0, &texels[0]);
                    tx.surface.read(&tx.surface, c, u0, v1, &texels[1]);
                    tx.surface.read(&tx.surface, c, u1, v0, &texels[2]);
                    tx.surface.read(&tx.surface, c, u1, v1, &texels[3]);
                    u = (u >> 12) & 0xF; 
                    v = (v >> 12) & 0xF;
                    u += u>>3;
                    v += v>>3;
                    mm[0] = (0x10 - u) * (0x10 - v);
                    mm[1] = (0x10 - u) * v;
                    mm[2] = u * (0x10 - v);
                    mm[3] = 0x100 - (mm[0] + mm[1] + mm[2]);
                    for (int j=0 ; j<4 ; j++) {
                        texel.s[j] = texels[0].s[j];
                        if (!texel.s[j]) continue;
                        texel.s[j] += 8;
                        texel.c[j] =    texels[0].c[j]*mm[0] +
                                        texels[1].c[j]*mm[1] +
                                        texels[2].c[j]*mm[2] +
                                        texels[3].c[j]*mm[3] ;
                    }
                }

                // Texture environnement...
                for (int j=0 ; j<4 ; j++) {
                    uint32_t& Cf = fragment.c[j];
                    uint32_t& Ct = texel.c[j];
                    uint8_t& sf  = fragment.s[j];
                    uint8_t& st  = texel.s[j];
                    uint32_t At = texel.c[0];
                    uint8_t sat = texel.s[0];
                    switch (tx.env) {
                    case GGL_REPLACE:
                        if (st) {
                            Cf = Ct;
                            sf = st;
                        }
                        break;
                    case GGL_MODULATE:
                        if (st) {
                            uint32_t factor = Ct + (Ct>>(st-1));
                            Cf = (Cf * factor) >> st;
                        }
                        break;
                    case GGL_DECAL:
                        if (sat) {
                            rescale(Cf, sf, Ct, st);
                            Cf += ((Ct - Cf) * (At + (At>>(sat-1)))) >> sat;
                        }
                        break;
                    case GGL_BLEND:
                        if (st) {
                            uint32_t Cc = tx.env_color[i];
                            if (sf>8)       Cc = (Cc * ((1<<sf)-1))>>8;
                            else if (sf<8)  Cc = (Cc - (Cc>>(8-sf)))>>(8-sf);
                            uint32_t factor = Ct + (Ct>>(st-1));
                            Cf = ((((1<<st) - factor) * Cf) + Ct*Cc)>>st;
                        }
                        break;
                    }
                }
            }
		}
    
        // coverage application
        if (enables & GGL_ENABLE_AA) {
            int16_t cf = *covPtr++;
            fragment.c[0] = (int64_t(fragment.c[0]) * cf) >> 15;
        }
        
        // alpha-test
        if (enables & GGL_ENABLE_ALPHA_TEST) {
            GGLcolor ref = c->state.alpha_test.ref;
            GGLcolor alpha = (uint64_t(fragment.c[0]) *
                    ((1<<GGL_COLOR_BITS)-1)) / ((1<<fragment.s[0])-1);
            switch (c->state.alpha_test.func) {
            case GGL_NEVER:     goto discard;
            case GGL_LESS:      if (alpha<ref)  break; goto discard;
            case GGL_EQUAL:     if (alpha==ref) break; goto discard;
            case GGL_LEQUAL:    if (alpha<=ref) break; goto discard;
            case GGL_GREATER:   if (alpha>ref)  break; goto discard;
            case GGL_NOTEQUAL:  if (alpha!=ref) break; goto discard;
            case GGL_GEQUAL:    if (alpha>=ref) break; goto discard;
            }
        }
        
        // depth test
        if (c->state.buffers.depth.format) {
            if (enables & GGL_ENABLE_DEPTH_TEST) {
                surface_t* cb = &(c->state.buffers.depth);
                uint16_t* p = (uint16_t*)(cb->data)+(x+(cb->stride*y));
                uint16_t zz = uint32_t(z)>>(16);
                uint16_t depth = *p;
                switch (c->state.depth_test.func) {
                case GGL_NEVER:     goto discard;
                case GGL_LESS:      if (zz<depth)    break; goto discard;
                case GGL_EQUAL:     if (zz==depth)   break; goto discard;
                case GGL_LEQUAL:    if (zz<=depth)   break; goto discard;
                case GGL_GREATER:   if (zz>depth)    break; goto discard;
                case GGL_NOTEQUAL:  if (zz!=depth)   break; goto discard;
                case GGL_GEQUAL:    if (zz>=depth)   break; goto discard;
                }
                // depth buffer is not enabled, if depth-test is not enabled
/*
        fragment.s[1] = fragment.s[2] =
        fragment.s[3] = fragment.s[0] = 8;
        fragment.c[1] = 
        fragment.c[2] = 
        fragment.c[3] = 
        fragment.c[0] = 255 - (zz>>8);
*/
                if (c->state.mask.depth) {
                    *p = zz;
                }
            }
        }

        // fog
        if (enables & GGL_ENABLE_FOG) {
            for (int i=1 ; i<=3 ; i++) {
                GGLfixed fc = (c->state.fog.color[i] * 0x10000) / 0xFF;
                uint32_t& c = fragment.c[i];
                uint8_t& s  = fragment.s[i];
                c = (c * 0x10000) / ((1<<s)-1);
                c = gglMulAddx(c, f, gglMulx(fc, 0x10000 - f));