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fuchsia / third_party / android / platform / system / core / 9871efb4e59ecf8ac778d22d7b834abea619e2bd / . / libpixelflinger / trap.cpp
blob: 234bfdde103563c405c6840b306dec1af3244d4a [file] [log] [blame]
/* 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.
*/
#define LOG_TAG "pixelflinger-trap"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <cutils/memory.h>
#include <log/log.h>
#include "trap.h"
#include "picker.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;
ALOGD(" 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);
ny = gglMulx(ny, norm, 21);
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;
aapolyx(con, v[0], 4);
}
// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Rect
#endif
void recti_validate(void *con, GGLint l, GGLint t, GGLint r, GGLint b)
{
GGL_CONTEXT(c, con);
ggl_pick(c);
c->procs.recti = recti;
c->procs.recti(con, l, t, r, b);
}
void recti(void* con, GGLint l, GGLint t, GGLint r, GGLint b)
{
GGL_CONTEXT(c, con);
// scissor...
if (l < GGLint(c->state.scissor.left))
l = GGLint(c->state.scissor.left);
if (t < GGLint(c->state.scissor.top))
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) {
c->iterators.xl = l;
c->iterators.xr = r;
c->init_y(c, t);
c->rect(c, yc);
}
}
// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Triangle / Debugging
#endif
static void scanline_set(context_t* c)
{
int32_t x = c->iterators.xl;
size_t ct = c->iterators.xr - x;
int32_t y = c->iterators.y;
surface_t* cb = &(c->state.buffers.color);
const GGLFormat* fp = &(c->formats[cb->format]);
uint8_t* dst = reinterpret_cast<uint8_t*>(cb->data) +
(x + (cb->stride * y)) * fp->size;
const size_t size = ct * fp->size;
memset(dst, 0xFF, size);
}
static void trianglex_debug(void* con,
const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
{
GGL_CONTEXT(c, con);
if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
aa_trianglex(con,v0,v1,v2);
} else {
trianglex_big(con,v0,v1,v2);
}
void (*save_scanline)(context_t*) = c->scanline;
c->scanline = scanline_set;
linex(con, v0, v1, TRI_ONE);
linex(con, v1, v2, TRI_ONE);
linex(con, v2, v0, TRI_ONE);
c->scanline = save_scanline;
}
static void trianglex_xor(void* con,
const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
{
trianglex_big(con,v0,v1,v2);
trianglex_small(con,v0,v1,v2);
}
// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#pragma mark Triangle
#endif
void trianglex_validate(void *con,
const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
{
GGL_CONTEXT(c, con);
ggl_pick(c);
if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
c->procs.trianglex = DEBUG_TRANGLES ? trianglex_debug : aa_trianglex;
} else {
c->procs.trianglex = DEBUG_TRANGLES ? trianglex_debug : trianglex_big;
}
c->procs.trianglex(con, v0, v1, v2);
}
// ----------------------------------------------------------------------------
void trianglex_small(void* con,
const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
{
GGL_CONTEXT(c, con);
// vertices are in 28.4 fixed point, which allows
// us to use 32 bits multiplies below.
int32_t x0 = v0[0];
int32_t y0 = v0[1];
int32_t x1 = v1[0];
int32_t y1 = v1[1];
int32_t x2 = v2[0];
int32_t y2 = v2[1];
int32_t dx01 = x0 - x1;
int32_t dy20 = y2 - y0;
int32_t dy01 = y0 - y1;
int32_t dx20 = x2 - x0;
// The code below works only with CCW triangles
// so if we get a CW triangle, we need to swap two of its vertices
if (dx01*dy20 < dy01*dx20) {
swap(x0, x1);
swap(y0, y1);
dx01 = x0 - x1;
dy01 = y0 - y1;
dx20 = x2 - x0;
dy20 = y2 - y0;
}
int32_t dx12 = x1 - x2;
int32_t dy12 = y1 - y2;
// bounding box & scissor
const int32_t bminx = TRI_FLOOR(min(x0, x1, x2)) >> TRI_FRACTION_BITS;
const int32_t bminy = TRI_FLOOR(min(y0, y1, y2)) >> TRI_FRACTION_BITS;
const int32_t bmaxx = TRI_CEIL( max(x0, x1, x2)) >> TRI_FRACTION_BITS;
const int32_t bmaxy = TRI_CEIL( max(y0, y1, y2)) >> TRI_FRACTION_BITS;
const int32_t minx = max(bminx, c->state.scissor.left);
const int32_t miny = max(bminy, c->state.scissor.top);
const int32_t maxx = min(bmaxx, c->state.scissor.right);
const int32_t maxy = min(bmaxy, c->state.scissor.bottom);
if ((minx >= maxx) || (miny >= maxy))
return; // too small or clipped out...
// step equations to the bounding box and snap to pixel center
const int32_t my = (miny << TRI_FRACTION_BITS) + TRI_HALF;
const int32_t mx = (minx << TRI_FRACTION_BITS) + TRI_HALF;
int32_t ey0 = dy01 * (x0 - mx) - dx01 * (y0 - my);
int32_t ey1 = dy12 * (x1 - mx) - dx12 * (y1 - my);
int32_t ey2 = dy20 * (x2 - mx) - dx20 * (y2 - my);
// right-exclusive fill rule, to avoid rare cases
// of over drawing
if (dy01<0 || (dy01 == 0 && dx01>0)) ey0++;
if (dy12<0 || (dy12 == 0 && dx12>0)) ey1++;
if (dy20<0 || (dy20 == 0 && dx20>0)) ey2++;
c->init_y(c, miny);
for (int32_t y = miny; y < maxy; y++) {
int32_t ex0 = ey0;
int32_t ex1 = ey1;
int32_t ex2 = ey2;
int32_t xl, xr;
for (xl=minx ; xl<maxx ; xl++) {
if (ex0>0 && ex1>0 && ex2>0)
break; // all strictly positive
ex0 -= dy01 << TRI_FRACTION_BITS;
ex1 -= dy12 << TRI_FRACTION_BITS;
ex2 -= dy20 << TRI_FRACTION_BITS;
}
xr = xl;
for ( ; xr<maxx ; xr++) {
if (!(ex0>0 && ex1>0 && ex2>0))
break; // not all strictly positive
ex0 -= dy01 << TRI_FRACTION_BITS;
ex1 -= dy12 << TRI_FRACTION_BITS;
ex2 -= dy20 << TRI_FRACTION_BITS;
}
if (xl < xr) {
c->iterators.xl = xl;
c->iterators.xr = xr;
c->scanline(c);
}
c->step_y(c);
ey0 += dx01 << TRI_FRACTION_BITS;
ey1 += dx12 << TRI_FRACTION_BITS;
ey2 += dx20 << TRI_FRACTION_BITS;
}
}
// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#endif
// the following routine fills a triangle via edge stepping, which
// unfortunately requires divisions in the setup phase to get right,
// it should probably only be used for relatively large trianges
// x = y*DX/DY (ou DX and DY are constants, DY > 0, et y >= 0)
//
// for an equation of the type:
// x' = y*K/2^p (with K and p constants "carefully chosen")
//
// We can now do a DDA without precision loss. We define 'e' by:
// x' - x = y*(DX/DY - K/2^p) = y*e
//
// If we choose K = round(DX*2^p/DY) then,
// abs(e) <= 1/2^(p+1) by construction
//
// therefore abs(x'-x) = y*abs(e) <= y/2^(p+1) <= DY/2^(p+1) <= DMAX/2^(p+1)
//
// which means that if DMAX <= 2^p, therefore abs(x-x') <= 1/2, including
// at the last line. In fact, it's even a strict inequality except in one
// extrem case (DY == DMAX et e = +/- 1/2)
//
// Applying that to our coordinates, we need 2^p >= 4096*16 = 65536
// so p = 16 is enough, we're so lucky!
const int TRI_ITERATORS_BITS = 16;
struct Edge
{
int32_t x; // edge position in 16.16 coordinates
int32_t x_incr; // on each step, increment x by that amount
int32_t y_top; // starting scanline, 16.4 format
int32_t y_bot;
};
static void
edge_dump( Edge* edge )
{
ALOGI( " top=%d (%.3f) bot=%d (%.3f) x=%d (%.3f) ix=%d (%.3f)",
edge->y_top, edge->y_top/float(TRI_ONE),
edge->y_bot, edge->y_bot/float(TRI_ONE),
edge->x, edge->x/float(FIXED_ONE),
edge->x_incr, edge->x_incr/float(FIXED_ONE) );
}
static void
triangle_dump_edges( Edge* edges,
int count )
{
ALOGI( "%d edge%s:\n", count, count == 1 ? "" : "s" );
for ( ; count > 0; count--, edges++ )
edge_dump( edges );
}
// the following function sets up an edge, it assumes
// that ymin and ymax are in already in the 'reduced'
// format
static __attribute__((noinline))
void edge_setup(
Edge* edges,
int* pcount,
const GGLcoord* p1,
const GGLcoord* p2,
int32_t ymin,
int32_t ymax )
{
const GGLfixed* top = p1;
const GGLfixed* bot = p2;
Edge* edge = edges + *pcount;
if (top[1] > bot[1]) {
swap(top, bot);
}
int y1 = top[1] | 1;
int y2 = bot[1] | 1;
int dy = y2 - y1;
if ( dy == 0 || y1 > ymax || y2 < ymin )
return;
if ( y1 > ymin )
ymin = TRI_SNAP_NEXT_HALF(y1);
if ( y2 < ymax )
ymax = TRI_SNAP_PREV_HALF(y2);
if ( ymin > ymax ) // when the edge doesn't cross any scanline
return;
const int x1 = top[0];
const int dx = bot[0] - x1;
const int shift = TRI_ITERATORS_BITS - TRI_FRACTION_BITS;
// setup edge fields
// We add 0.5 to edge->x here because it simplifies the rounding
// in triangle_sweep_edges() -- this doesn't change the ordering of 'x'
edge->x = (x1 << shift) + (1LU << (TRI_ITERATORS_BITS-1));
edge->x_incr = 0;
edge->y_top = ymin;
edge->y_bot = ymax;
if (ggl_likely(ymin <= ymax && dx)) {
edge->x_incr = gglDivQ16(dx, dy);
}
if (ggl_likely(y1 < ymin)) {
int32_t xadjust = (edge->x_incr * (ymin-y1)) >> TRI_FRACTION_BITS;
edge->x += xadjust;
}
++*pcount;
}
static void
triangle_sweep_edges( Edge* left,
Edge* right,
int ytop,
int ybot,
context_t* c )
{
int count = ((ybot - ytop)>>TRI_FRACTION_BITS) + 1;
if (count<=0) return;
// sort the edges horizontally
if ((left->x > right->x) ||
((left->x == right->x) && (left->x_incr > right->x_incr))) {
swap(left, right);
}
int left_x = left->x;
int right_x = right->x;
const int left_xi = left->x_incr;
const int right_xi = right->x_incr;
left->x += left_xi * count;
right->x += right_xi * count;
const int xmin = c->state.scissor.left;
const int xmax = c->state.scissor.right;
do {
// horizontal scissoring
const int32_t xl = max(left_x >> TRI_ITERATORS_BITS, xmin);
const int32_t xr = min(right_x >> TRI_ITERATORS_BITS, xmax);
left_x += left_xi;
right_x += right_xi;
// invoke the scanline rasterizer
if (ggl_likely(xl < xr)) {
c->iterators.xl = xl;
c->iterators.xr = xr;
c->scanline(c);
}
c->step_y(c);
} while (--count);
}
void trianglex_big(void* con,
const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
{
GGL_CONTEXT(c, con);
Edge edges[3];
int num_edges = 0;
int32_t ymin = TRI_FROM_INT(c->state.scissor.top) + TRI_HALF;
int32_t ymax = TRI_FROM_INT(c->state.scissor.bottom) - TRI_HALF;
edge_setup( edges, &num_edges, v0, v1, ymin, ymax );
edge_setup( edges, &num_edges, v0, v2, ymin, ymax );
edge_setup( edges, &num_edges, v1, v2, ymin, ymax );
if (ggl_unlikely(num_edges<2)) // for really tiny triangles that don't
return; // cross any scanline centers
Edge* left = &edges[0];
Edge* right = &edges[1];
Edge* other = &edges[2];
int32_t y_top = min(left->y_top, right->y_top);
int32_t y_bot = max(left->y_bot, right->y_bot);
if (ggl_likely(num_edges==3)) {
y_top = min(y_top, edges[2].y_top);
y_bot = max(y_bot, edges[2].y_bot);
if (edges[0].y_top > y_top) {
other = &edges[0];
left = &edges[2];
} else if (edges[1].y_top > y_top) {
other = &edges[1];
right = &edges[2];
}
}
c->init_y(c, y_top >> TRI_FRACTION_BITS);
int32_t y_mid = min(left->y_bot, right->y_bot);
triangle_sweep_edges( left, right, y_top, y_mid, c );
// second scanline sweep loop, if necessary
y_mid += TRI_ONE;
if (y_mid <= y_bot) {
((left->y_bot == y_bot) ? right : left) = other;
if (other->y_top < y_mid) {
other->x += other->x_incr;
}
triangle_sweep_edges( left, right, y_mid, y_bot, c );
}
}
void aa_trianglex(void* con,
const GGLcoord* a, const GGLcoord* b, const GGLcoord* c)
{
GGLcoord pts[6] = { a[0], a[1], b[0], b[1], c[0], c[1] };
aapolyx(con, pts, 3);
}
// ----------------------------------------------------------------------------
#if 0
#pragma mark -
#endif
struct AAEdge
{
GGLfixed x; // edge position in 12.16 coordinates
GGLfixed x_incr; // on each y step, increment x by that amount
GGLfixed y_incr; // on each x step, increment y by that amount
int16_t y_top; // starting scanline, 12.4 format
int16_t y_bot; // starting scanline, 12.4 format
void dump();
};
void AAEdge::dump()
{
float tri = 1.0f / TRI_ONE;
float iter = 1.0f / (1<<TRI_ITERATORS_BITS);
float fix = 1.0f / FIXED_ONE;
ALOGD( "x=%08x (%.3f), "
"x_incr=%08x (%.3f), y_incr=%08x (%.3f), "
"y_top=%08x (%.3f), y_bot=%08x (%.3f) ",
x, x*fix,
x_incr, x_incr*iter,
y_incr, y_incr*iter,
y_top, y_top*tri,
y_bot, y_bot*tri );
}
// the following function sets up an edge, it assumes
// that ymin and ymax are in already in the 'reduced'
// format
static __attribute__((noinline))
void aa_edge_setup(
AAEdge* edges,
int* pcount,
const GGLcoord* p1,
const GGLcoord* p2,
int32_t ymin,
int32_t ymax )
{
const GGLfixed* top = p1;
const GGLfixed* bot = p2;
AAEdge* edge = edges + *pcount;
if (top[1] > bot[1])
swap(top, bot);
int y1 = top[1];
int y2 = bot[1];
int dy = y2 - y1;
if (dy==0 || y1>ymax || y2<ymin)
return;
if (y1 > ymin)
ymin = y1;
if (y2 < ymax)
ymax = y2;
const int x1 = top[0];
const int dx = bot[0] - x1;
const int shift = FIXED_BITS - TRI_FRACTION_BITS;
// setup edge fields
edge->x = x1 << shift;
edge->x_incr = 0;
edge->y_top = ymin;
edge->y_bot = ymax;
edge->y_incr = 0x7FFFFFFF;
if (ggl_likely(ymin <= ymax && dx)) {
edge->x_incr = gglDivQ16(dx, dy);
if (dx != 0) {
edge->y_incr = abs(gglDivQ16(dy, dx));
}
}
if (ggl_likely(y1 < ymin)) {
int32_t xadjust = (edge->x_incr * (ymin-y1))
>> (TRI_FRACTION_BITS + TRI_ITERATORS_BITS - FIXED_BITS);
edge->x += xadjust;
}
++*pcount;
}
typedef int (*compar_t)(const void*, const void*);
static int compare_edges(const AAEdge *e0, const AAEdge *e1) {
if (e0->y_top > e1->y_top) return 1;
if (e0->y_top < e1->y_top) return -1;
if (e0->x > e1->x) return 1;
if (e0->x < e1->x) return -1;
if (e0->x_incr > e1->x_incr) return 1;
if (e0->x_incr < e1->x_incr) return -1;
return 0; // same edges, should never happen
}
static inline
void SET_COVERAGE(int16_t*& p, int32_t value, ssize_t n)
{
android_memset16((uint16_t*)p, value, n*2);
p += n;
}
static inline
void ADD_COVERAGE(int16_t*& p, int32_t value)
{
value = *p + value;
if (value >= 0x8000)
value = 0x7FFF;
*p++ = value;
}
static inline
void SUB_COVERAGE(int16_t*& p, int32_t value)
{
value = *p - value;
value &= ~(value>>31);
*p++ = value;
}
void aapolyx(void* con,
const GGLcoord* pts, int count)
{
/*
* NOTE: This routine assumes that the polygon has been clipped to the
* viewport already, that is, no vertex lies outside of the framebuffer.
* If this happens, the code below won't corrupt memory but the
* coverage values may not be correct.
*/
GGL_CONTEXT(c, con);
// we do only quads for now (it's used for thick lines)
if ((count>4) || (count<2)) return;
// take scissor into account
const int xmin = c->state.scissor.left;
const int xmax = c->state.scissor.right;
if (xmin >= xmax) return;
// generate edges from the vertices
int32_t ymin = TRI_FROM_INT(c->state.scissor.top);
int32_t ymax = TRI_FROM_INT(c->state.scissor.bottom);
if (ymin >= ymax) return;
AAEdge edges[4];
int num_edges = 0;
GGLcoord const * p = pts;
for (int i=0 ; i<count-1 ; i++, p+=2) {
aa_edge_setup(edges, &num_edges, p, p+2, ymin, ymax);
}
aa_edge_setup(edges, &num_edges, p, pts, ymin, ymax );
if (ggl_unlikely(num_edges<2))
return;
// sort the edge list top to bottom, left to right.
qsort(edges, num_edges, sizeof(AAEdge), (compar_t)compare_edges);
int16_t* const covPtr = c->state.buffers.coverage;
memset(covPtr+xmin, 0, (xmax-xmin)*sizeof(*covPtr));
// now, sweep all edges in order
// start with the 2 first edges. We know that they share their top
// vertex, by construction.
int i = 2;
AAEdge* left = &edges[0];
AAEdge* right = &edges[1];
int32_t yt = left->y_top;
GGLfixed l = left->x;
GGLfixed r = right->x;
int retire = 0;
int16_t* coverage;
// at this point we can initialize the rasterizer
c->init_y(c, yt>>TRI_FRACTION_BITS);
c->iterators.xl = xmax;
c->iterators.xr = xmin;
do {
int32_t y = min(min(left->y_bot, right->y_bot), TRI_FLOOR(yt + TRI_ONE));
const int32_t shift = TRI_FRACTION_BITS + TRI_ITERATORS_BITS - FIXED_BITS;
const int cf_shift = (1 + TRI_FRACTION_BITS*2 + TRI_ITERATORS_BITS - 15);
// compute xmin and xmax for the left edge
GGLfixed l_min = gglMulAddx(left->x_incr, y - left->y_top, left->x, shift);
GGLfixed l_max = l;
l = l_min;
if (l_min > l_max)
swap(l_min, l_max);
// compute xmin and xmax for the right edge
GGLfixed r_min = gglMulAddx(right->x_incr, y - right->y_top, right->x, shift);
GGLfixed r_max = r;
r = r_min;
if (r_min > r_max)
swap(r_min, r_max);
// make sure we're not touching coverage values outside of the
// framebuffer
l_min &= ~(l_min>>31);
r_min &= ~(r_min>>31);
l_max &= ~(l_max>>31);
r_max &= ~(r_max>>31);
if (gglFixedToIntFloor(l_min) >= xmax) l_min = gglIntToFixed(xmax)-1;
if (gglFixedToIntFloor(r_min) >= xmax) r_min = gglIntToFixed(xmax)-1;
if (gglFixedToIntCeil(l_max) >= xmax) l_max = gglIntToFixed(xmax)-1;
if (gglFixedToIntCeil(r_max) >= xmax) r_max = gglIntToFixed(xmax)-1;
// compute the integer versions of the above
const GGLfixed l_min_i = gglFloorx(l_min);
const GGLfixed l_max_i = gglCeilx (l_max);
const GGLfixed r_min_i = gglFloorx(r_min);
const GGLfixed r_max_i = gglCeilx (r_max);
// clip horizontally using the scissor
const int xml = max(xmin, gglFixedToIntFloor(l_min_i));
const int xmr = min(xmax, gglFixedToIntFloor(r_max_i));
// if we just stepped to a new scanline, render the previous one.
// and clear the coverage buffer
if (retire) {
if (c->iterators.xl < c->iterators.xr)
c->scanline(c);
c->step_y(c);
memset(covPtr+xmin, 0, (xmax-xmin)*sizeof(*covPtr));
c->iterators.xl = xml;
c->iterators.xr = xmr;
} else {
// update the horizontal range of this scanline
c->iterators.xl = min(c->iterators.xl, xml);
c->iterators.xr = max(c->iterators.xr, xmr);
}
coverage = covPtr + gglFixedToIntFloor(l_min_i);
if (l_min_i == gglFloorx(l_max)) {
/*
* fully traverse this pixel vertically
* l_max
* +-----/--+ yt
* | / |
* | / |
* | / |
* +-/------+ y
* l_min (l_min_i + TRI_ONE)
*/
GGLfixed dx = l_max - l_min;
int32_t dy = y - yt;
int cf = gglMulx((dx >> 1) + (l_min_i + FIXED_ONE - l_max), dy,
FIXED_BITS + TRI_FRACTION_BITS - 15);
ADD_COVERAGE(coverage, cf);
// all pixels on the right have cf = 1.0
} else {
/*
* spans several pixels in one scanline
* l_max
* +--------+--/-----+ yt
* | |/ |
* | /| |
* | / | |
* +---/----+--------+ y
* l_min (l_min_i + TRI_ONE)
*/
// handle the first pixel separately...
const int32_t y_incr = left->y_incr;
int32_t dx = TRI_FROM_FIXED(l_min_i - l_min) + TRI_ONE;
int32_t cf = (dx * dx * y_incr) >> cf_shift;
ADD_COVERAGE(coverage, cf);
// following pixels get covered by y_incr, but we need
// to fix-up the cf to account for previous partial pixel
dx = TRI_FROM_FIXED(l_min - l_min_i);
cf -= (dx * dx * y_incr) >> cf_shift;
for (int x = l_min_i+FIXED_ONE ; x < l_max_i-FIXED_ONE ; x += FIXED_ONE) {
cf += y_incr >> (TRI_ITERATORS_BITS-15);
ADD_COVERAGE(coverage, cf);
}
// and the last pixel
dx = TRI_FROM_FIXED(l_max - l_max_i) - TRI_ONE;
cf += (dx * dx * y_incr) >> cf_shift;
ADD_COVERAGE(coverage, cf);
}
// now, fill up all fully covered pixels
coverage = covPtr + gglFixedToIntFloor(l_max_i);
int cf = ((y - yt) << (15 - TRI_FRACTION_BITS));
if (ggl_likely(cf >= 0x8000)) {
SET_COVERAGE(coverage, 0x7FFF, ((r_max - l_max_i)>>FIXED_BITS)+1);
} else {
for (int x=l_max_i ; x<r_max ; x+=FIXED_ONE) {
ADD_COVERAGE(coverage, cf);
}
}
// subtract the coverage of the right edge
coverage = covPtr + gglFixedToIntFloor(r_min_i);
if (r_min_i == gglFloorx(r_max)) {
GGLfixed dx = r_max - r_min;
int32_t dy = y - yt;
int cf = gglMulx((dx >> 1) + (r_min_i + FIXED_ONE - r_max), dy,
FIXED_BITS + TRI_FRACTION_BITS - 15);
SUB_COVERAGE(coverage, cf);
// all pixels on the right have cf = 1.0
} else {
// handle the first pixel separately...
const int32_t y_incr = right->y_incr;
int32_t dx = TRI_FROM_FIXED(r_min_i - r_min) + TRI_ONE;
int32_t cf = (dx * dx * y_incr) >> cf_shift;
SUB_COVERAGE(coverage, cf);
// following pixels get covered by y_incr, but we need
// to fix-up the cf to account for previous partial pixel
dx = TRI_FROM_FIXED(r_min - r_min_i);
cf -= (dx * dx * y_incr) >> cf_shift;
for (int x = r_min_i+FIXED_ONE ; x < r_max_i-FIXED_ONE ; x += FIXED_ONE) {
cf += y_incr >> (TRI_ITERATORS_BITS-15);
SUB_COVERAGE(coverage, cf);
}
// and the last pixel
dx = TRI_FROM_FIXED(r_max - r_max_i) - TRI_ONE;
cf += (dx * dx * y_incr) >> cf_shift;
SUB_COVERAGE(coverage, cf);
}
// did we reach the end of an edge? if so, get a new one.
if (y == left->y_bot || y == right->y_bot) {
// bail out if we're done
if (i>=num_edges)
break;
if (y == left->y_bot)
left = &edges[i++];
if (y == right->y_bot)
right = &edges[i++];
}
// next scanline
yt = y;
// did we just finish a scanline?
retire = (y << (32-TRI_FRACTION_BITS)) == 0;
} while (true);
// render the last scanline
if (c->iterators.xl < c->iterators.xr)
c->scanline(c);
}
}; // namespace android