trap.cpp

Android 一些工具

/* libs/pixelflinger/trap.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 <assert.h>
#include <stdio.h>
#include <stdlib.h>

#include "trap.h"
#include "picker.h"

#include <cutils/log.h>
#include <cutils/memory.h>

namespace android {

// ----------------------------------------------------------------------------

// enable to see triangles edges
#define DEBUG_TRANGLES  0

// ----------------------------------------------------------------------------

static void pointx_validate(void *con, const GGLcoord* c, GGLcoord r);
static void pointx(void *con, const GGLcoord* c, GGLcoord r);
static void aa_pointx(void *con, const GGLcoord* c, GGLcoord r);
static void aa_nice_pointx(void *con, const GGLcoord* c, GGLcoord r);

static void linex_validate(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w);
static void linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w);
static void aa_linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w);

static void recti_validate(void* c, GGLint l, GGLint t, GGLint r, GGLint b); 
static void recti(void* c, GGLint l, GGLint t, GGLint r, GGLint b); 

static void trianglex_validate(void*,
        const GGLcoord*, const GGLcoord*, const GGLcoord*);
static void trianglex_small(void*,
        const GGLcoord*, const GGLcoord*, const GGLcoord*);
static void trianglex_big(void*,
        const GGLcoord*, const GGLcoord*, const GGLcoord*);
static void aa_trianglex(void*,
        const GGLcoord*, const GGLcoord*, const GGLcoord*);
static void trianglex_debug(void* con,
        const GGLcoord*, const GGLcoord*, const GGLcoord*);

static void aapolyx(void* con,
        const GGLcoord* pts, int count);

static inline int min(int a, int b) CONST;
static inline int max(int a, int b) CONST;
static inline int min(int a, int b, int c) CONST;
static inline int max(int a, int b, int c) CONST;

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Tools
#endif

inline int min(int a, int b) {
    return a<b ? a : b;
}
inline int max(int a, int b) {
    return a<b ? b : a;
}
inline int min(int a, int b, int c) {
    return min(a,min(b,c));
}
inline int max(int a, int b, int c) {
    return max(a,max(b,c));
}

template <typename T>
static inline void swap(T& a, T& b) {
    T t(a);
    a = b;
    b = t;
}

static void
triangle_dump_points( const GGLcoord*  v0,
                      const GGLcoord*  v1,
				 	  const GGLcoord*  v2 )
{
    float tri = 1.0f / TRI_ONE;
  LOGD(     "  P0=(%.3f, %.3f)  [%08x, %08x]\n"
            "  P1=(%.3f, %.3f)  [%08x, %08x]\n"
            "  P2=(%.3f, %.3f)  [%08x, %08x]\n",
		v0[0]*tri, v0[1]*tri, v0[0], v0[1],
		v1[0]*tri, v1[1]*tri, v1[0], v1[1],
		v2[0]*tri, v2[1]*tri, v2[0], v2[1] );
}

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Misc
#endif

void ggl_init_trap(context_t* c)
{
    ggl_state_changed(c, GGL_PIXEL_PIPELINE_STATE|GGL_TMU_STATE|GGL_CB_STATE);
}

void ggl_state_changed(context_t* c, int flags)
{
    if (ggl_likely(!c->dirty)) {
        c->procs.pointx     = pointx_validate;
        c->procs.linex      = linex_validate;
        c->procs.recti      = recti_validate;
        c->procs.trianglex  = trianglex_validate;
    }
    c->dirty |= uint32_t(flags);
}

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Point
#endif

void pointx_validate(void *con, const GGLcoord* v, GGLcoord rad)
{
    GGL_CONTEXT(c, con);
    ggl_pick(c);
    if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
        if (c->state.enables & GGL_ENABLE_POINT_AA_NICE) {
            c->procs.pointx = aa_nice_pointx;
        } else {
            c->procs.pointx = aa_pointx;
        }
    } else {
        c->procs.pointx = pointx;
    }
    c->procs.pointx(con, v, rad);
}

void pointx(void *con, const GGLcoord* v, GGLcoord rad)
{
    GGL_CONTEXT(c, con);
    GGLcoord halfSize = TRI_ROUND(rad) >> 1;
    if (halfSize == 0)
        halfSize = TRI_HALF;
    GGLcoord xc = v[0]; 
    GGLcoord yc = v[1];
    if (halfSize & TRI_HALF) { // size odd
        xc = TRI_FLOOR(xc) + TRI_HALF;
        yc = TRI_FLOOR(yc) + TRI_HALF;
    } else { // size even
        xc = TRI_ROUND(xc);
        yc = TRI_ROUND(yc);
    }
    GGLint l = (xc - halfSize) >> TRI_FRACTION_BITS;
    GGLint t = (yc - halfSize) >> TRI_FRACTION_BITS;
    GGLint r = (xc + halfSize) >> TRI_FRACTION_BITS;
    GGLint b = (yc + halfSize) >> TRI_FRACTION_BITS;
    recti(c, l, t, r, b);
}

// This way of computing the coverage factor, is more accurate and gives
// better results for small circles, but it is also a lot slower.
// Here we use super-sampling.
static int32_t coverageNice(GGLcoord x, GGLcoord y, 
        GGLcoord rmin, GGLcoord rmax, GGLcoord rr)
{
    const GGLcoord d2 = x*x + y*y;
    if (d2 >= rmax) return 0;
    if (d2 < rmin)  return 0x7FFF;

    const int kSamples              =  4;
    const int kInc                  =  4;    // 1/4 = 0.25
    const int kCoverageUnit         =  1;    // 1/(4^2) = 0.0625
    const GGLcoord kCoordOffset     = -6;    // -0.375

    int hits = 0;
    int x_sample = x + kCoordOffset;
    for (int i=0 ; i<kSamples ; i++, x_sample += kInc) {
        const int xval = rr - (x_sample * x_sample);
        int y_sample = y + kCoordOffset;
        for (int j=0 ; j<kSamples ; j++, y_sample += kInc) {
            if (xval - (y_sample * y_sample) > 0)
                hits += kCoverageUnit;
        }
    }
    return min(0x7FFF, hits << (15 - kSamples));
}


void aa_nice_pointx(void *con, const GGLcoord* v, GGLcoord size)
{
    GGL_CONTEXT(c, con);

    GGLcoord rad = ((size + 1)>>1);
    GGLint l = (v[0] - rad) >> TRI_FRACTION_BITS;
    GGLint t = (v[1] - rad) >> TRI_FRACTION_BITS;
    GGLint r = (v[0] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
    GGLint b = (v[1] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
    GGLcoord xstart = TRI_FROM_INT(l) - v[0] + TRI_HALF; 
    GGLcoord ystart = TRI_FROM_INT(t) - v[1] + TRI_HALF; 

    // scissor...
    if (l < GGLint(c->state.scissor.left)) {
        xstart += TRI_FROM_INT(c->state.scissor.left-l);
        l = GGLint(c->state.scissor.left);
    }
    if (t < GGLint(c->state.scissor.top)) {
        ystart += TRI_FROM_INT(c->state.scissor.top-t);
        t = GGLint(c->state.scissor.top);
    }
    if (r > GGLint(c->state.scissor.right)) {
        r = GGLint(c->state.scissor.right);
    }
    if (b > GGLint(c->state.scissor.bottom)) {
        b = GGLint(c->state.scissor.bottom);
    }

    int xc = r - l;
    int yc = b - t;
    if (xc>0 && yc>0) {
        int16_t* covPtr = c->state.buffers.coverage;
        const int32_t sqr2Over2 = 0xC; // rounded up
        GGLcoord rr = rad*rad;
        GGLcoord rmin = (rad - sqr2Over2)*(rad - sqr2Over2);
        GGLcoord rmax = (rad + sqr2Over2)*(rad + sqr2Over2);
        GGLcoord y = ystart;
        c->iterators.xl = l;
        c->iterators.xr = r;
        c->init_y(c, t);
        do {
            // compute coverage factors for each pixel
            GGLcoord x = xstart;
            for (int i=l ; i<r ; i++) {
                covPtr[i] = coverageNice(x, y, rmin, rmax, rr);
                x += TRI_ONE;
            }
            y += TRI_ONE;
            c->scanline(c);
            c->step_y(c);
        } while (--yc);
    }
}

// This is a cheap way of computing the coverage factor for a circle.
// We just lerp between the circles of radii r-sqrt(2)/2 and r+sqrt(2)/2
static inline int32_t coverageFast(GGLcoord x, GGLcoord y,
        GGLcoord rmin, GGLcoord rmax, GGLcoord scale)
{
    const GGLcoord d2 = x*x + y*y;
    if (d2 >= rmax) return 0;
    if (d2 < rmin)  return 0x7FFF;
    return 0x7FFF - (d2-rmin)*scale;
}

void aa_pointx(void *con, const GGLcoord* v, GGLcoord size)
{
    GGL_CONTEXT(c, con);

    GGLcoord rad = ((size + 1)>>1);
    GGLint l = (v[0] - rad) >> TRI_FRACTION_BITS;
    GGLint t = (v[1] - rad) >> TRI_FRACTION_BITS;
    GGLint r = (v[0] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
    GGLint b = (v[1] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
    GGLcoord xstart = TRI_FROM_INT(l) - v[0] + TRI_HALF; 
    GGLcoord ystart = TRI_FROM_INT(t) - v[1] + TRI_HALF; 

    // scissor...
    if (l < GGLint(c->state.scissor.left)) {
        xstart += TRI_FROM_INT(c->state.scissor.left-l);
        l = GGLint(c->state.scissor.left);
    }
    if (t < GGLint(c->state.scissor.top)) {
        ystart += TRI_FROM_INT(c->state.scissor.top-t);
        t = GGLint(c->state.scissor.top);
    }
    if (r > GGLint(c->state.scissor.right)) {
        r = GGLint(c->state.scissor.right);
    }
    if (b > GGLint(c->state.scissor.bottom)) {
        b = GGLint(c->state.scissor.bottom);
    }

    int xc = r - l;
    int yc = b - t;
    if (xc>0 && yc>0) {
        int16_t* covPtr = c->state.buffers.coverage;
        rad <<= 4;
        const int32_t sqr2Over2 = 0xB5;    // fixed-point 24.8
        GGLcoord rmin = rad - sqr2Over2;
        GGLcoord rmax = rad + sqr2Over2;
        GGLcoord scale;
        rmin *= rmin;
        rmax *= rmax;
        scale = 0x800000 / (rmax - rmin);
        rmin >>= 8;
        rmax >>= 8;

        GGLcoord y = ystart;
        c->iterators.xl = l;
        c->iterators.xr = r;
        c->init_y(c, t);

        do {
            // compute coverage factors for each pixel
            GGLcoord x = xstart;
            for (int i=l ; i<r ; i++) {
                covPtr[i] = coverageFast(x, y, rmin, rmax, scale);
                x += TRI_ONE;
            }
            y += TRI_ONE;
            c->scanline(c);
            c->step_y(c);
        } while (--yc);
    }
}

// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Line
#endif

void linex_validate(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w)
{
    GGL_CONTEXT(c, con);
    ggl_pick(c);
    if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
        c->procs.linex = aa_linex;
    } else {
        c->procs.linex = linex;
    }
    c->procs.linex(con, v0, v1, w);
}

static void linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord width)
{
    GGL_CONTEXT(c, con);
    GGLcoord v[4][2];
    v[0][0] = v0[0];    v[0][1] = v0[1];
    v[1][0] = v1[0];    v[1][1] = v1[1];
    v0 = v[0];
    v1 = v[1];
    const GGLcoord dx = abs(v0[0] - v1[0]);
    const GGLcoord dy = abs(v0[1] - v1[1]);
    GGLcoord nx, ny;
    nx = ny = 0;

    GGLcoord halfWidth = TRI_ROUND(width) >> 1;
    if (halfWidth == 0)
        halfWidth = TRI_HALF;

    ((dx > dy) ? ny : nx) = halfWidth;
    v[2][0] = v1[0];    v[2][1] = v1[1];
    v[3][0] = v0[0];    v[3][1] = v0[1];
    v[0][0] += nx;      v[0][1] += ny;
    v[1][0] += nx;      v[1][1] += ny;
    v[2][0] -= nx;      v[2][1] -= ny;
    v[3][0] -= nx;      v[3][1] -= ny;
    trianglex_big(con, v[0], v[1], v[2]);
    trianglex_big(con, v[0], v[2], v[3]);
}

static void aa_linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord width)
{
    GGL_CONTEXT(c, con);
    GGLcoord v[4][2];
    v[0][0] = v0[0];    v[0][1] = v0[1];
    v[1][0] = v1[0];    v[1][1] = v1[1];
    v0 = v[0];
    v1 = v[1];
    
    const GGLcoord dx = v0[0] - v1[0];
    const GGLcoord dy = v0[1] - v1[1];
    GGLcoord nx = -dy;
    GGLcoord ny =  dx;

    // generally, this will be well below 1.0
    const GGLfixed norm = gglMulx(width, gglSqrtRecipx(nx*nx+ny*ny), 4);
    nx = gglMulx(nx, norm, 21);