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draw: fix flat shading and screen-space linear interpolation in clipper

Browse source 
This includes:
- picking up correctly which attributes are flatshaded and which are
  noperspective

- copying the flatshaded attributes when needed, including the
  non-built-in ones

- correctly interpolating the noperspective attributes in screen-space
  instead than in a 3d-correct fashion.

Signed-off-by: Olivier Galibert <galibert@pobox.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
This commit is contained in:
Olivier Galibert 2012-06-19 20:51:19 +02:00 • committed by Brian Paul
parent cfc5b30941
commit 4625a9b1ad
1 changed files with 113 additions and 31 deletions
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144
src/gallium/auxiliary/draw/draw_pipe_clip.c
View file

@ -39,6 +39,7 @@
#include "draw_vs.h"
#include "draw_pipe.h"
#include "draw_fs.h"
#ifndef IS_NEGATIVE
@ -56,11 +57,12 @@
struct clip_stage {
struct draw_stage stage; /**< base class */
/* Basically duplicate some of the flatshading logic here:
*/
boolean flat;
uint num_color_attribs;
uint color_attribs[4]; /* front/back primary/secondary colors */
/* List of the attributes to be flatshaded. */
uint num_flat_attribs;
uint flat_attribs[PIPE_MAX_SHADER_OUTPUTS];
/* Mask of attributes in noperspective mode */
boolean noperspective_attribs[PIPE_MAX_SHADER_OUTPUTS];
float (*plane)[4];
};
@ -91,17 +93,16 @@ static void interp_attr( float dst[4],
/**
* Copy front/back, primary/secondary colors from src vertex to dst vertex.
* Used when flat shading.
* Copy flat shaded attributes src vertex to dst vertex.
*/
static void copy_colors( struct draw_stage *stage,
struct vertex_header *dst,
const struct vertex_header *src )
static void copy_flat( struct draw_stage *stage,
struct vertex_header *dst,
const struct vertex_header *src )
{
const struct clip_stage *clipper = clip_stage(stage);
uint i;
for (i = 0; i < clipper->num_color_attribs; i++) {
const uint attr = clipper->color_attribs[i];
for (i = 0; i < clipper->num_flat_attribs; i++) {
const uint attr = clipper->flat_attribs[i];
COPY_4FV(dst->data[attr], src->data[attr]);
}
}
@ -120,6 +121,7 @@ static void interp( const struct clip_stage *clip,
const unsigned pos_attr = draw_current_shader_position_output(clip->stage.draw);
const unsigned clip_attr = draw_current_shader_clipvertex_output(clip->stage.draw);
unsigned j;
float t_nopersp;
/* Vertex header.
*/
@ -148,12 +150,36 @@ static void interp( const struct clip_stage *clip,
dst->data[pos_attr][2] = pos[2] * oow * scale[2] + trans[2];
dst->data[pos_attr][3] = oow;
}
/**
* Compute the t in screen-space instead of 3d space to use
* for noperspective interpolation.
*
* The points can be aligned with the X axis, so in that case try
* the Y. When both points are at the same screen position, we can
* pick whatever value (the interpolated point won't be in front
* anyway), so just use the 3d t.
*/
{
int k;
t_nopersp = t;
for (k = 0; k < 2; k++)
if (in->data[pos_attr][k] != out->data[pos_attr][k]) {
t_nopersp = (dst->data[pos_attr][k] - out->data[pos_attr][k]) /
(in->data[pos_attr][k] - out->data[pos_attr][k]);
break;
}
}
/* Other attributes
*/
for (j = 0; j < nr_attrs; j++) {
if (j != pos_attr && j != clip_attr)
interp_attr(dst->data[j], t, in->data[j], out->data[j]);
if (j != pos_attr && j != clip_attr) {
if (clip->noperspective_attribs[j])
interp_attr(dst->data[j], t_nopersp, in->data[j], out->data[j]);
else
interp_attr(dst->data[j], t, in->data[j], out->data[j]);
}
}
}
@ -406,14 +432,14 @@ do_clip_tri( struct draw_stage *stage,
/* If flat-shading, copy provoking vertex color to polygon vertex[0]
*/
if (n >= 3) {
if (clipper->flat) {
if (clipper->num_flat_attribs) {
if (stage->draw->rasterizer->flatshade_first) {
if (inlist[0] != header->v[0]) {
assert(tmpnr < MAX_CLIPPED_VERTICES + 1);
if (tmpnr >= MAX_CLIPPED_VERTICES + 1)
return;
inlist[0] = dup_vert(stage, inlist[0], tmpnr++);
copy_colors(stage, inlist[0], header->v[0]);
copy_flat(stage, inlist[0], header->v[0]);
}
}
else {
@ -422,7 +448,7 @@ do_clip_tri( struct draw_stage *stage,
if (tmpnr >= MAX_CLIPPED_VERTICES + 1)
return;
inlist[0] = dup_vert(stage, inlist[0], tmpnr++);
copy_colors(stage, inlist[0], header->v[2]);
copy_flat(stage, inlist[0], header->v[2]);
}
}
}
@ -471,10 +497,7 @@ do_clip_line( struct draw_stage *stage,
if (v0->clipmask) {
interp( clipper, stage->tmp[0], t0, v0, v1 );
if (clipper->flat)
copy_colors(stage, stage->tmp[0], v0);
copy_flat(stage, stage->tmp[0], v0);
newprim.v[0] = stage->tmp[0];
}
else {
@ -548,21 +571,80 @@ static void
clip_init_state( struct draw_stage *stage )
{
struct clip_stage *clipper = clip_stage( stage );
const struct draw_vertex_shader *vs = stage->draw->vs.vertex_shader;
const struct draw_fragment_shader *fs = stage->draw->fs.fragment_shader;
uint i;
clipper->flat = stage->draw->rasterizer->flatshade ? TRUE : FALSE;
/* We need to know for each attribute what kind of interpolation is
* done on it (flat, smooth or noperspective). But the information
* is not directly accessible for outputs, only for inputs. So we
* have to match semantic name and index between the VS (or GS/ES)
* outputs and the FS inputs to get to the interpolation mode.
*
* The only hitch is with gl_FrontColor/gl_BackColor which map to
* gl_Color, and their Secondary versions. First there are (up to)
* two outputs for one input, so we tuck the information in a
* specific array. Second if they don't have qualifiers, the
* default value has to be picked from the global shade mode.
*/
if (clipper->flat) {
const struct draw_vertex_shader *vs = stage->draw->vs.vertex_shader;
uint i;
/* First pick up the interpolation mode for
* gl_Color/gl_SecondaryColor, with the correct default.
*/
int indexed_interp[2];
indexed_interp[0] = indexed_interp[1] = stage->draw->rasterizer->flatshade ?
TGSI_INTERPOLATE_CONSTANT : TGSI_INTERPOLATE_PERSPECTIVE;
clipper->num_color_attribs = 0;
for (i = 0; i < vs->info.num_outputs; i++) {
if (vs->info.output_semantic_name[i] == TGSI_SEMANTIC_COLOR ||
vs->info.output_semantic_name[i] == TGSI_SEMANTIC_BCOLOR) {
clipper->color_attribs[clipper->num_color_attribs++] = i;
}
for (i = 0; i < fs->info.num_inputs; i++) {
if (fs->info.input_semantic_name[i] == TGSI_SEMANTIC_COLOR) {
if (fs->info.input_interpolate[i] != TGSI_INTERPOLATE_COLOR)
indexed_interp[fs->info.input_semantic_index[i]] = fs->info.input_interpolate[i];
}
}
/* Then resolve the interpolation mode for every output attribute.
*
* Given how the rest of the code, the most efficient way is to
* have a vector of flat-mode attributes, and a mask for
* noperspective attributes.
*/
clipper->num_flat_attribs = 0;
memset(clipper->noperspective_attribs, 0, sizeof(clipper->noperspective_attribs));
for (i = 0; i < vs->info.num_outputs; i++) {
/* Find the interpolation mode for a specific attribute
*/
int interp;
/* If it's gl_{Front,Back}{,Secondary}Color, pick up the mode
* from the array we've filled before. */
if (vs->info.output_semantic_name[i] == TGSI_SEMANTIC_COLOR ||
vs->info.output_semantic_name[i] == TGSI_SEMANTIC_BCOLOR) {
interp = indexed_interp[vs->info.output_semantic_index[i]];
} else {
/* Otherwise, search in the FS inputs, with a decent default
* if we don't find it.
*/
uint j;
interp = TGSI_INTERPOLATE_PERSPECTIVE;
for (j = 0; j < fs->info.num_inputs; j++) {
if (vs->info.output_semantic_name[i] == fs->info.input_semantic_name[j] &&
vs->info.output_semantic_index[i] == fs->info.input_semantic_index[j]) {
interp = fs->info.input_interpolate[j];
break;
}
}
}
/* If it's flat, add it to the flat vector. Otherwise update
* the noperspective mask.
*/
if (interp == TGSI_INTERPOLATE_CONSTANT) {
clipper->flat_attribs[clipper->num_flat_attribs] = i;
clipper->num_flat_attribs++;
} else
clipper->noperspective_attribs[i] = interp == TGSI_INTERPOLATE_LINEAR;
}
stage->tri = clip_tri;
stage->line = clip_line;