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/**************************************************************************
*
* Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
* IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
**************************************************************************/
/*
* Binning code for triangles
*/
#include "lp_setup_context.h"
#include "lp_rast.h"
#include "util/u_math.h"
#include "util/u_memory.h"
#define NUM_CHANNELS 4
/**
* Compute a0 for a constant-valued coefficient (GL_FLAT shading).
*/
static void constant_coef( struct lp_rast_triangle *tri,
unsigned slot,
const float value,
unsigned i )
{
tri->inputs.a0[slot][i] = value;
tri->inputs.dadx[slot][i] = 0.0f;
tri->inputs.dady[slot][i] = 0.0f;
}
/**
* Compute a0, dadx and dady for a linearly interpolated coefficient,
* for a triangle.
*/
static void linear_coef( struct lp_rast_triangle *tri,
float oneoverarea,
unsigned slot,
const float (*v1)[4],
const float (*v2)[4],
const float (*v3)[4],
unsigned vert_attr,
unsigned i)
{
float a1 = v1[vert_attr][i];
float a2 = v2[vert_attr][i];
float a3 = v3[vert_attr][i];
float da12 = a1 - a2;
float da31 = a3 - a1;
float dadx = (da12 * tri->dy31 - tri->dy12 * da31) * oneoverarea;
float dady = (da31 * tri->dx12 - tri->dx31 * da12) * oneoverarea;
tri->inputs.dadx[slot][i] = dadx;
tri->inputs.dady[slot][i] = dady;
/* calculate a0 as the value which would be sampled for the
* fragment at (0,0), taking into account that we want to sample at
* pixel centers, in other words (0.5, 0.5).
*
* this is neat but unfortunately not a good way to do things for
* triangles with very large values of dadx or dady as it will
* result in the subtraction and re-addition from a0 of a very
* large number, which means we'll end up loosing a lot of the
* fractional bits and precision from a0. the way to fix this is
* to define a0 as the sample at a pixel center somewhere near vmin
* instead - i'll switch to this later.
*/
tri->inputs.a0[slot][i] = (v1[vert_attr][i] -
(dadx * (v1[0][0] - 0.5f) +
dady * (v1[0][1] - 0.5f)));
}
/**
* Compute a0, dadx and dady for a perspective-corrected interpolant,
* for a triangle.
* We basically multiply the vertex value by 1/w before computing
* the plane coefficients (a0, dadx, dady).
* Later, when we compute the value at a particular fragment position we'll
* divide the interpolated value by the interpolated W at that fragment.
*/
static void perspective_coef( struct lp_rast_triangle *tri,
float oneoverarea,
unsigned slot,
const float (*v1)[4],
const float (*v2)[4],
const float (*v3)[4],
unsigned vert_attr,
unsigned i)
{
/* premultiply by 1/w (v[0][3] is always 1/w):
*/
float a1 = v1[vert_attr][i] * v1[0][3];
float a2 = v2[vert_attr][i] * v2[0][3];
float a3 = v3[vert_attr][i] * v3[0][3];
float da12 = a1 - a2;
float da31 = a3 - a1;
float dadx = (da12 * tri->dy31 - tri->dy12 * da31) * oneoverarea;
float dady = (da31 * tri->dx12 - tri->dx31 * da12) * oneoverarea;
tri->inputs.dadx[slot][i] = dadx;
tri->inputs.dady[slot][i] = dady;
tri->inputs.a0[slot][i] = (a1 -
(dadx * (v1[0][0] - 0.5f) +
dady * (v1[0][1] - 0.5f)));
}
/**
* Special coefficient setup for gl_FragCoord.
* X and Y are trivial
* Z and W are copied from position_coef which should have already been computed.
* We could do a bit less work if we'd examine gl_FragCoord's swizzle mask.
*/
static void
setup_fragcoord_coef(struct lp_rast_triangle *tri,
float oneoverarea,
unsigned slot,
const float (*v1)[4],
const float (*v2)[4],
const float (*v3)[4])
{
/*X*/
tri->inputs.a0[slot][0] = 0.0;
tri->inputs.dadx[slot][0] = 1.0;
tri->inputs.dady[slot][0] = 0.0;
/*Y*/
tri->inputs.a0[slot][1] = 0.0;
tri->inputs.dadx[slot][1] = 0.0;
tri->inputs.dady[slot][1] = 1.0;
/*Z*/
linear_coef(tri, oneoverarea, slot, v1, v2, v3, 0, 2);
/*W*/
linear_coef(tri, oneoverarea, slot, v1, v2, v3, 0, 3);
}
static void setup_facing_coef( struct lp_rast_triangle *tri,
unsigned slot,
boolean frontface )
{
constant_coef( tri, slot, 1.0f - frontface, 0 );
constant_coef( tri, slot, 0.0f, 1 ); /* wasted */
constant_coef( tri, slot, 0.0f, 2 ); /* wasted */
constant_coef( tri, slot, 0.0f, 3 ); /* wasted */
}
/**
* Compute the tri->coef[] array dadx, dady, a0 values.
*/
static void setup_tri_coefficients( struct setup_context *setup,
struct lp_rast_triangle *tri,
float oneoverarea,
const float (*v1)[4],
const float (*v2)[4],
const float (*v3)[4],
boolean frontface)
{
struct lp_scene *scene = lp_setup_get_current_scene(setup);
unsigned slot;
/* Allocate space for the a0, dadx and dady arrays
*/
{
unsigned bytes = (setup->fs.nr_inputs + 1) * 4 * sizeof(float);
tri->inputs.a0 = lp_scene_alloc_aligned( scene, bytes, 16 );
tri->inputs.dadx = lp_scene_alloc_aligned( scene, bytes, 16 );
tri->inputs.dady = lp_scene_alloc_aligned( scene, bytes, 16 );
}
/* The internal position input is in slot zero:
*/
setup_fragcoord_coef(tri, oneoverarea, 0, v1, v2, v3);
/* setup interpolation for all the remaining attributes:
*/
for (slot = 0; slot < setup->fs.nr_inputs; slot++) {
unsigned vert_attr = setup->fs.input[slot].src_index;
unsigned i;
switch (setup->fs.input[slot].interp) {
case LP_INTERP_CONSTANT:
for (i = 0; i < NUM_CHANNELS; i++)
constant_coef(tri, slot+1, v3[vert_attr][i], i);
break;
case LP_INTERP_LINEAR:
for (i = 0; i < NUM_CHANNELS; i++)
linear_coef(tri, oneoverarea, slot+1, v1, v2, v3, vert_attr, i);
break;
case LP_INTERP_PERSPECTIVE:
for (i = 0; i < NUM_CHANNELS; i++)
perspective_coef(tri, oneoverarea, slot+1, v1, v2, v3, vert_attr, i);
break;
case LP_INTERP_POSITION:
/* XXX: fix me - duplicates the values in slot zero.
*/
setup_fragcoord_coef(tri, oneoverarea, slot+1, v1, v2, v3);
break;
case LP_INTERP_FACING:
setup_facing_coef(tri, slot+1, frontface);
break;
default:
assert(0);
}
}
}
static inline int subpixel_snap( float a )
{
return util_iround(FIXED_ONE * a - (FIXED_ONE / 2));
}
/**
* Do basic setup for triangle rasterization and determine which
* framebuffer tiles are touched. Put the triangle in the scene's
* bins for the tiles which we overlap.
*/
static void
do_triangle_ccw(struct setup_context *setup,
const float (*v1)[4],
const float (*v2)[4],
const float (*v3)[4],
boolean frontfacing )
{
/* x/y positions in fixed point */
const int x1 = subpixel_snap(v1[0][0]);
const int x2 = subpixel_snap(v2[0][0]);
const int x3 = subpixel_snap(v3[0][0]);
const int y1 = subpixel_snap(v1[0][1]);
const int y2 = subpixel_snap(v2[0][1]);
const int y3 = subpixel_snap(v3[0][1]);
struct lp_scene *scene = lp_setup_get_current_scene(setup);
struct lp_rast_triangle *tri = lp_scene_alloc_aligned( scene, sizeof *tri, 16 );
float area, oneoverarea;
int minx, maxx, miny, maxy;
tri->dx12 = x1 - x2;
tri->dx23 = x2 - x3;
tri->dx31 = x3 - x1;
tri->dy12 = y1 - y2;
tri->dy23 = y2 - y3;
tri->dy31 = y3 - y1;
area = (tri->dx12 * tri->dy31 -
tri->dx31 * tri->dy12);
/* Cull non-ccw and zero-sized triangles.
*
* XXX: subject to overflow??
*/
if (area <= 0.0f) {
lp_scene_putback_data( scene, sizeof *tri );
return;
}
/* Bounding rectangle (in pixels) */
minx = (MIN3(x1, x2, x3) + (FIXED_ONE-1)) >> FIXED_ORDER;
maxx = (MAX3(x1, x2, x3) + (FIXED_ONE-1)) >> FIXED_ORDER;
miny = (MIN3(y1, y2, y3) + (FIXED_ONE-1)) >> FIXED_ORDER;
maxy = (MAX3(y1, y2, y3) + (FIXED_ONE-1)) >> FIXED_ORDER;
if (miny == maxy ||
minx == maxx) {
lp_scene_putback_data( scene, sizeof *tri );
return;
}
/*
*/
oneoverarea = ((float)FIXED_ONE) / (float)area;
/* Setup parameter interpolants:
*/
setup_tri_coefficients( setup, tri, oneoverarea, v1, v2, v3, frontfacing );
/* half-edge constants, will be interated over the whole render target.
*/
tri->c1 = tri->dy12 * x1 - tri->dx12 * y1;
tri->c2 = tri->dy23 * x2 - tri->dx23 * y2;
tri->c3 = tri->dy31 * x3 - tri->dx31 * y3;
/* correct for top-left fill convention:
*/
if (tri->dy12 < 0 || (tri->dy12 == 0 && tri->dx12 > 0)) tri->c1++;
if (tri->dy23 < 0 || (tri->dy23 == 0 && tri->dx23 > 0)) tri->c2++;
if (tri->dy31 < 0 || (tri->dy31 == 0 && tri->dx31 > 0)) tri->c3++;
tri->dy12 *= FIXED_ONE;
tri->dy23 *= FIXED_ONE;
tri->dy31 *= FIXED_ONE;
tri->dx12 *= FIXED_ONE;
tri->dx23 *= FIXED_ONE;
tri->dx31 *= FIXED_ONE;
/* find trivial reject offsets for each edge for a single-pixel
* sized block. These will be scaled up at each recursive level to
* match the active blocksize. Scaling in this way works best if
* the blocks are square.
*/
tri->eo1 = 0;
if (tri->dy12 < 0) tri->eo1 -= tri->dy12;
if (tri->dx12 > 0) tri->eo1 += tri->dx12;
tri->eo2 = 0;
if (tri->dy23 < 0) tri->eo2 -= tri->dy23;
if (tri->dx23 > 0) tri->eo2 += tri->dx23;
tri->eo3 = 0;
if (tri->dy31 < 0) tri->eo3 -= tri->dy31;
if (tri->dx31 > 0) tri->eo3 += tri->dx31;
/* Calculate trivial accept offsets from the above.
*/
tri->ei1 = tri->dx12 - tri->dy12 - tri->eo1;
tri->ei2 = tri->dx23 - tri->dy23 - tri->eo2;
tri->ei3 = tri->dx31 - tri->dy31 - tri->eo3;
{
const int xstep1 = -tri->dy12;
const int xstep2 = -tri->dy23;
const int xstep3 = -tri->dy31;
const int ystep1 = tri->dx12;
const int ystep2 = tri->dx23;
const int ystep3 = tri->dx31;
int qx, qy, ix, iy;
int i = 0;
for (qy = 0; qy < 2; qy++) {
for (qx = 0; qx < 2; qx++) {
for (iy = 0; iy < 2; iy++) {
for (ix = 0; ix < 2; ix++, i++) {
int x = qx * 2 + ix;
int y = qy * 2 + iy;
tri->inputs.step[0][i] = x * xstep1 + y * ystep1;
tri->inputs.step[1][i] = x * xstep2 + y * ystep2;
tri->inputs.step[2][i] = x * xstep3 + y * ystep3;
}
}
}
}
}
/*
* All fields of 'tri' are now set. The remaining code here is
* concerned with binning.
*/
/* Convert to tile coordinates:
*/
minx = minx / TILE_SIZE;
miny = miny / TILE_SIZE;
maxx = maxx / TILE_SIZE;
maxy = maxy / TILE_SIZE;
/* Clamp maxx, maxy to framebuffer size
*/
maxx = MIN2(maxx, scene->tiles_x - 1);
maxy = MIN2(maxy, scene->tiles_y - 1);
/* Determine which tile(s) intersect the triangle's bounding box
*/
if (miny == maxy && minx == maxx)
{
/* Triangle is contained in a single tile:
*/
lp_scene_bin_command( scene, minx, miny, lp_rast_triangle,
lp_rast_arg_triangle(tri) );
}
else
{
int c1 = (tri->c1 +
tri->dx12 * miny * TILE_SIZE -
tri->dy12 * minx * TILE_SIZE);
int c2 = (tri->c2 +
tri->dx23 * miny * TILE_SIZE -
tri->dy23 * minx * TILE_SIZE);
int c3 = (tri->c3 +
tri->dx31 * miny * TILE_SIZE -
tri->dy31 * minx * TILE_SIZE);
int ei1 = tri->ei1 << TILE_ORDER;
int ei2 = tri->ei2 << TILE_ORDER;
int ei3 = tri->ei3 << TILE_ORDER;
int eo1 = tri->eo1 << TILE_ORDER;
int eo2 = tri->eo2 << TILE_ORDER;
int eo3 = tri->eo3 << TILE_ORDER;
int xstep1 = -(tri->dy12 << TILE_ORDER);
int xstep2 = -(tri->dy23 << TILE_ORDER);
int xstep3 = -(tri->dy31 << TILE_ORDER);
int ystep1 = tri->dx12 << TILE_ORDER;
int ystep2 = tri->dx23 << TILE_ORDER;
int ystep3 = tri->dx31 << TILE_ORDER;
int x, y;
/* Trivially accept or reject blocks, else jump to per-pixel
* examination above.
*/
for (y = miny; y <= maxy; y++)
{
int cx1 = c1;
int cx2 = c2;
int cx3 = c3;
boolean in = FALSE; /* are we inside the triangle? */
for (x = minx; x <= maxx; x++)
{
if (cx1 + eo1 < 0 ||
cx2 + eo2 < 0 ||
cx3 + eo3 < 0)
{
/* do nothing */
if (in)
break; /* exiting triangle, all done with this row */
}
else if (cx1 + ei1 > 0 &&
cx2 + ei2 > 0 &&
cx3 + ei3 > 0)
{
in = TRUE;
/* triangle covers the whole tile- shade whole tile */
if(setup->fs.current.opaque) {
lp_scene_bin_reset( scene, x, y );
lp_scene_bin_command( scene, x, y,
lp_rast_set_state,
lp_rast_arg_state(setup->fs.stored) );
}
lp_scene_bin_command( scene, x, y,
lp_rast_shade_tile,
lp_rast_arg_inputs(&tri->inputs) );
}
else
{
in = TRUE;
/* shade partial tile */
lp_scene_bin_command( scene, x, y,
lp_rast_triangle,
lp_rast_arg_triangle(tri) );
}
/* Iterate cx values across the region:
*/
cx1 += xstep1;
cx2 += xstep2;
cx3 += xstep3;
}
/* Iterate c values down the region:
*/
c1 += ystep1;
c2 += ystep2;
c3 += ystep3;
}
}
}
static void triangle_cw( struct setup_context *setup,
const float (*v0)[4],
const float (*v1)[4],
const float (*v2)[4] )
{
do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface );
}
static void triangle_ccw( struct setup_context *setup,
const float (*v0)[4],
const float (*v1)[4],
const float (*v2)[4] )
{
do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface );
}
static void triangle_both( struct setup_context *setup,
const float (*v0)[4],
const float (*v1)[4],
const float (*v2)[4] )
{
/* edge vectors e = v0 - v2, f = v1 - v2 */
const float ex = v0[0][0] - v2[0][0];
const float ey = v0[0][1] - v2[0][1];
const float fx = v1[0][0] - v2[0][0];
const float fy = v1[0][1] - v2[0][1];
/* det = cross(e,f).z */
if (ex * fy - ey * fx < 0.0f)
triangle_ccw( setup, v0, v1, v2 );
else
triangle_cw( setup, v0, v1, v2 );
}
static void triangle_nop( struct setup_context *setup,
const float (*v0)[4],
const float (*v1)[4],
const float (*v2)[4] )
{
}
void
lp_setup_choose_triangle( struct setup_context *setup )
{
switch (setup->cullmode) {
case PIPE_WINDING_NONE:
setup->triangle = triangle_both;
break;
case PIPE_WINDING_CCW:
setup->triangle = triangle_cw;
break;
case PIPE_WINDING_CW:
setup->triangle = triangle_ccw;
break;
default:
setup->triangle = triangle_nop;
break;
}
}
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