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mesa, st/mesa: fix gl_FragCoord with FBOs in Gallium

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gl_FragCoord.y needs to be flipped upside down if a FBO is bound.

This fixes:
- piglit/fbo-fragcoord
- https://bugs.freedesktop.org/show_bug.cgi?id=29420

Here I add a new program state STATE_FB_WPOS_Y_TRANSFORM, which is set based
on whether a FBO is bound. The state contains a pair of transformations.
It can be either (XY=identity, ZW=transformY) if a FBO is bound,
or (XY=transformY, ZW=identity) otherwise, where identity = (1, 0),
transformY = (-1, height-1).

A classic driver (or st/mesa) may, based on some other state, choose whether
to use XY or ZW, thus negate the conditional "if (is a FBO bound) ...".
The reason for this is that a Gallium driver is allowed to only support WPOS
relative to either the lower left or the upper left corner, so we must flip
the Y axis accordingly again. (the "invert" parameter in emit_wpos_inversion)

NOTE: This is a candidate for the 7.9 branch.

Signed-off-by: Marek Olšák <maraeo@gmail.com>
Signed-off-by: Brian Paul <brianp@vmware.com>
(cherry picked from commit d531f9c2f5)
This commit is contained in:
Marek Olšák 2010-12-02 20:39:59 +01:00
parent 564a6a15fe
commit 2cb8522523
3 changed files with 51 additions and 15 deletions
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22
src/mesa/program/prog_statevars.c
View file

@ -584,6 +584,24 @@ _mesa_fetch_state(GLcontext *ctx, const gl_state_index state[],
value[3] = 0.0F;
return;
case STATE_FB_WPOS_Y_TRANSFORM:
/* A driver may negate this conditional by using ZW swizzle
* instead of XY (based on e.g. some other state). */
if (ctx->DrawBuffer->Name != 0) {
/* Identity (XY) followed by flipping Y upside down (ZW). */
value[0] = 1.0F;
value[1] = 0.0F;
value[2] = -1.0F;
value[3] = (GLfloat) (ctx->DrawBuffer->Height - 1);
} else {
/* Flipping Y upside down (XY) followed by identity (ZW). */
value[0] = -1.0F;
value[1] = (GLfloat) (ctx->DrawBuffer->Height - 1);
value[2] = 1.0F;
value[3] = 0.0F;
}
return;
case STATE_ROT_MATRIX_0:
{
const int unit = (int) state[2];
@ -711,6 +729,7 @@ _mesa_program_state_flags(const gl_state_index state[STATE_LENGTH])
return _NEW_PIXEL;
case STATE_FB_SIZE:
case STATE_FB_WPOS_Y_TRANSFORM:
return _NEW_BUFFERS;
default:
@ -925,6 +944,9 @@ append_token(char *dst, gl_state_index k)
case STATE_FB_SIZE:
append(dst, "FbSize");
break;
case STATE_FB_WPOS_Y_TRANSFORM:
append(dst, "FbWposYTransform");
break;
case STATE_ROT_MATRIX_0:
append(dst, "rotMatrixRow0");
break;

1
src/mesa/program/prog_statevars.h
View file

@ -120,6 +120,7 @@ typedef enum gl_state_index_ {
STATE_PCM_BIAS, /**< Post color matrix RGBA bias */
STATE_SHADOW_AMBIENT, /**< ARB_shadow_ambient fail value; token[2] is texture unit index */
STATE_FB_SIZE, /**< (width-1, height-1, 0, 0) */
STATE_FB_WPOS_Y_TRANSFORM, /**< (1, 0, -1, height-1) if a FBO is bound, (-1, height-1, 1, 0) otherwise */
STATE_ROT_MATRIX_0, /**< ATI_envmap_bumpmap, rot matrix row 0 */
STATE_ROT_MATRIX_1, /**< ATI_envmap_bumpmap, rot matrix row 1 */
STATE_INTERNAL_DRIVER /* first available state index for drivers (must be last) */

43
src/mesa/state_tracker/st_mesa_to_tgsi.c
View file

@ -760,10 +760,13 @@ emit_adjusted_wpos( struct st_translate *t,
/**
* Emit the TGSI instructions for inverting the WPOS y coordinate.
* This code is unavoidable because it also depends on whether
* a FBO is bound (STATE_FB_WPOS_Y_TRANSFORM).
*/
static void
emit_inverted_wpos( struct st_translate *t,
const struct gl_program *program )
emit_wpos_inversion( struct st_translate *t,
const struct gl_program *program,
boolean invert)
{
struct ureg_program *ureg = t->ureg;
@ -771,17 +774,17 @@ emit_inverted_wpos( struct st_translate *t,
* Need to replace instances of INPUT[WPOS] with temp T
* where T = INPUT[WPOS] by y is inverted.
*/
static const gl_state_index winSizeState[STATE_LENGTH]
= { STATE_INTERNAL, STATE_FB_SIZE, 0, 0, 0 };
static const gl_state_index wposTransformState[STATE_LENGTH]
= { STATE_INTERNAL, STATE_FB_WPOS_Y_TRANSFORM, 0, 0, 0 };
/* XXX: note we are modifying the incoming shader here! Need to
* do this before emitting the constant decls below, or this
* will be missed:
*/
unsigned winHeightConst = _mesa_add_state_reference(program->Parameters,
winSizeState);
unsigned wposTransConst = _mesa_add_state_reference(program->Parameters,
wposTransformState);
struct ureg_src winsize = ureg_DECL_constant( ureg, winHeightConst );
struct ureg_src wpostrans = ureg_DECL_constant( ureg, wposTransConst );
struct ureg_dst wpos_temp;
struct ureg_src wpos_input = t->inputs[t->inputMapping[FRAG_ATTRIB_WPOS]];
@ -794,12 +797,23 @@ emit_inverted_wpos( struct st_translate *t,
ureg_MOV( ureg, wpos_temp, wpos_input );
}
/* SUB wpos_temp.y, winsize_const, wpos_input
*/
ureg_SUB( ureg,
ureg_writemask(wpos_temp, TGSI_WRITEMASK_Y ),
winsize,
wpos_input);
if (invert) {
/* MAD wpos_temp.y, wpos_input, wpostrans.xxxx, wpostrans.yyyy
*/
ureg_MAD( ureg,
ureg_writemask(wpos_temp, TGSI_WRITEMASK_Y ),
wpos_input,
ureg_scalar(wpostrans, 0),
ureg_scalar(wpostrans, 1));
} else {
/* MAD wpos_temp.y, wpos_input, wpostrans.zzzz, wpostrans.wwww
*/
ureg_MAD( ureg,
ureg_writemask(wpos_temp, TGSI_WRITEMASK_Y ),
wpos_input,
ureg_scalar(wpostrans, 2),
ureg_scalar(wpostrans, 3));
}
/* Use wpos_temp as position input from here on:
*/
@ -861,8 +875,7 @@ emit_wpos(struct st_context *st,
/* we invert after adjustment so that we avoid the MOV to temporary,
* and reuse the adjustment ADD instead */
if (invert)
emit_inverted_wpos(t, program);
emit_wpos_inversion(t, program, invert);
}