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/**************************************************************************
*
* Copyright 2010, VMware.
* 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 VMWARE 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 "util/u_math.h"
#include "util/u_memory.h"
#include "lp_perf.h"
#include "lp_setup_context.h"
#include "lp_setup_coef.h"
#include "lp_rast.h"
#include "lp_state_fs.h"
#if !defined(PIPE_ARCH_SSE)
/**
* Compute a0 for a constant-valued coefficient (GL_FLAT shading).
*/
static void constant_coef( struct lp_tri_info *info,
unsigned slot,
const float value,
unsigned i )
{
info->a0[slot][i] = value;
info->dadx[slot][i] = 0.0f;
info->dady[slot][i] = 0.0f;
}
static void linear_coef( struct lp_tri_info *info,
unsigned slot,
unsigned vert_attr,
unsigned i)
{
float a0 = info->v0[vert_attr][i];
float a1 = info->v1[vert_attr][i];
float a2 = info->v2[vert_attr][i];
float da01 = a0 - a1;
float da20 = a2 - a0;
float dadx = (da01 * info->dy20_ooa - info->dy01_ooa * da20);
float dady = (da20 * info->dx01_ooa - info->dx20_ooa * da01);
info->dadx[slot][i] = dadx;
info->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.
*/
info->a0[slot][i] = a0 - (dadx * info->x0_center +
dady * info->y0_center);
}
/**
* 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_tri_info *info,
unsigned slot,
unsigned vert_attr,
unsigned i)
{
/* premultiply by 1/w (v[0][3] is always 1/w):
*/
float a0 = info->v0[vert_attr][i] * info->v0[0][3];
float a1 = info->v1[vert_attr][i] * info->v1[0][3];
float a2 = info->v2[vert_attr][i] * info->v2[0][3];
float da01 = a0 - a1;
float da20 = a2 - a0;
float dadx = da01 * info->dy20_ooa - info->dy01_ooa * da20;
float dady = da20 * info->dx01_ooa - info->dx20_ooa * da01;
info->dadx[slot][i] = dadx;
info->dady[slot][i] = dady;
info->a0[slot][i] = a0 - (dadx * info->x0_center +
dady * info->y0_center);
}
/**
* 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_tri_info *info,
unsigned slot,
unsigned usage_mask)
{
/*X*/
if (usage_mask & TGSI_WRITEMASK_X) {
info->a0[slot][0] = 0.0;
info->dadx[slot][0] = 1.0;
info->dady[slot][0] = 0.0;
}
/*Y*/
if (usage_mask & TGSI_WRITEMASK_Y) {
info->a0[slot][1] = 0.0;
info->dadx[slot][1] = 0.0;
info->dady[slot][1] = 1.0;
}
/*Z*/
if (usage_mask & TGSI_WRITEMASK_Z) {
linear_coef(inputs, info, slot, 0, 2);
}
/*W*/
if (usage_mask & TGSI_WRITEMASK_W) {
linear_coef(inputs, info, slot, 0, 3);
}
}
/**
* Setup the fragment input attribute with the front-facing value.
* \param frontface is the triangle front facing?
*/
static void setup_facing_coef( struct lp_tri_info *info,
unsigned slot,
boolean frontface,
unsigned usage_mask)
{
/* convert TRUE to 1.0 and FALSE to -1.0 */
if (usage_mask & TGSI_WRITEMASK_X)
constant_coef( info, slot, 2.0f * frontface - 1.0f, 0 );
if (usage_mask & TGSI_WRITEMASK_Y)
constant_coef( info, slot, 0.0f, 1 ); /* wasted */
if (usage_mask & TGSI_WRITEMASK_Z)
constant_coef( info, slot, 0.0f, 2 ); /* wasted */
if (usage_mask & TGSI_WRITEMASK_W)
constant_coef( info, slot, 0.0f, 3 ); /* wasted */
}
/**
* Compute the tri->coef[] array dadx, dady, a0 values.
*/
void lp_setup_tri_coef( struct lp_setup_context *setup,
struct lp_rast_shader_inputs *inputs,
const float (*v0)[4],
const float (*v1)[4],
const float (*v2)[4],
boolean frontfacing)
{
unsigned fragcoord_usage_mask = TGSI_WRITEMASK_XYZ;
unsigned slot;
unsigned i;
struct lp_tri_info info;
float dx01 = v0[0][0] - v1[0][0];
float dy01 = v0[0][1] - v1[0][1];
float dx20 = v2[0][0] - v0[0][0];
float dy20 = v2[0][1] - v0[0][1];
float oneoverarea = 1.0f / (dx01 * dy20 - dx20 * dy01);
info.v0 = v0;
info.v1 = v1;
info.v2 = v2;
info.frontfacing = frontfacing;
info.x0_center = v0[0][0] - setup->pixel_offset;
info.y0_center = v0[0][1] - setup->pixel_offset;
info.dx01_ooa = dx01 * oneoverarea;
info.dx20_ooa = dx20 * oneoverarea;
info.dy01_ooa = dy01 * oneoverarea;
info.dy20_ooa = dy20 * oneoverarea;
info.a0 = GET_A0(inputs);
info.dadx = GET_DADX(inputs);
info.dady = GET_DADY(inputs);
/* 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 usage_mask = setup->fs.input[slot].usage_mask;
switch (setup->fs.input[slot].interp) {
case LP_INTERP_CONSTANT:
if (setup->flatshade_first) {
for (i = 0; i < NUM_CHANNELS; i++)
if (usage_mask & (1 << i))
constant_coef(&info, slot+1, info.v0[vert_attr][i], i);
}
else {
for (i = 0; i < NUM_CHANNELS; i++)
if (usage_mask & (1 << i))
constant_coef(&info, slot+1, info.v2[vert_attr][i], i);
}
break;
case LP_INTERP_LINEAR:
for (i = 0; i < NUM_CHANNELS; i++)
if (usage_mask & (1 << i))
linear_coef(&info, slot+1, vert_attr, i);
break;
case LP_INTERP_PERSPECTIVE:
for (i = 0; i < NUM_CHANNELS; i++)
if (usage_mask & (1 << i))
perspective_coef(&info, slot+1, vert_attr, i);
fragcoord_usage_mask |= TGSI_WRITEMASK_W;
break;
case LP_INTERP_POSITION:
/*
* The generated pixel interpolators will pick up the coeffs from
* slot 0, so all need to ensure that the usage mask is covers all
* usages.
*/
fragcoord_usage_mask |= usage_mask;
break;
case LP_INTERP_FACING:
setup_facing_coef(&info, slot+1, info.frontfacing, usage_mask);
break;
default:
assert(0);
}
}
/* The internal position input is in slot zero:
*/
setup_fragcoord_coef(&info, 0, fragcoord_usage_mask);
}
#else
extern void lp_setup_coef_dummy(void);
void lp_setup_coef_dummy(void)
{
}
#endif
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