/*
* Copyright 2014 VMware, Inc.
* 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 THE AUTHORS 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.
*/
/**
* This utility transforms the fragment shader to support anti-aliasing points.
*/
#include "util/u_debug.h"
#include "util/u_math.h"
#include "tgsi_info.h"
#include "tgsi_aa_point.h"
#include "tgsi_transform.h"
#define INVALID_INDEX 9999
struct aa_transform_context
{
struct tgsi_transform_context base;
unsigned tmp; // temp register
unsigned color_out; // frag color out register
unsigned color_tmp; // frag color temp register
unsigned num_tmp; // number of temp registers
unsigned num_imm; // number of immediates
unsigned num_input; // number of inputs
unsigned aa_point_coord_index;
};
static inline struct aa_transform_context *
aa_transform_context(struct tgsi_transform_context *ctx)
{
return (struct aa_transform_context *) ctx;
}
/**
* TGSI declaration transform callback.
*/
static void
aa_decl(struct tgsi_transform_context *ctx,
struct tgsi_full_declaration *decl)
{
struct aa_transform_context *ts = aa_transform_context(ctx);
if (decl->Declaration.File == TGSI_FILE_OUTPUT &&
decl->Semantic.Name == TGSI_SEMANTIC_COLOR &&
decl->Semantic.Index == 0) {
ts->color_out = decl->Range.First;
}
else if (decl->Declaration.File == TGSI_FILE_INPUT) {
ts->num_input++;
}
else if (decl->Declaration.File == TGSI_FILE_TEMPORARY) {
ts->num_tmp = MAX2(ts->num_tmp, decl->Range.Last + 1);
}
ctx->emit_declaration(ctx, decl);
}
/**
* TGSI immediate declaration transform callback.
*/
static void
aa_immediate(struct tgsi_transform_context *ctx,
struct tgsi_full_immediate *imm)
{
struct aa_transform_context *ts = aa_transform_context(ctx);
ctx->emit_immediate(ctx, imm);
ts->num_imm++;
}
/**
* TGSI transform prolog callback.
*/
static void
aa_prolog(struct tgsi_transform_context *ctx)
{
struct aa_transform_context *ts = aa_transform_context(ctx);
unsigned tmp0;
unsigned texIn;
unsigned imm;
/* Declare two temporary registers, one for temporary and
* one for color.
*/
ts->tmp = ts->num_tmp++;
ts->color_tmp = ts->num_tmp++;
tgsi_transform_temps_decl(ctx, ts->tmp, ts->color_tmp);
/* Declare new generic input/texcoord */
texIn = ts->num_input++;
tgsi_transform_input_decl(ctx, texIn, TGSI_SEMANTIC_GENERIC,
ts->aa_point_coord_index, TGSI_INTERPOLATE_LINEAR);
/* Declare extra immediates */
imm = ts->num_imm++;
tgsi_transform_immediate_decl(ctx, 0.5, 0.5, 0.45, 1.0);
/*
* Emit code to compute fragment coverage.
* The point always has radius 0.5. The threshold value will be a
* value less than, but close to 0.5, such as 0.45.
* We compute a coverage factor from the distance and threshold.
* If the coverage is negative, the fragment is outside the circle and
* it's discarded.
* If the coverage is >= 1, the fragment is fully inside the threshold
* distance. We limit/clamp the coverage to 1.
* Otherwise, the fragment is between the threshold value and 0.5 and we
* compute a coverage value in [0,1].
*
* Input reg (texIn) usage:
* texIn.x = x point coord in [0,1]
* texIn.y = y point coord in [0,1]
* texIn.z = "k" the smoothing threshold distance
* texIn.w = unused
*
* Temp reg (t0) usage:
* t0.x = distance of fragment from center point
* t0.y = boolean, is t0.x > 0.5, also misc temp usage
* t0.z = temporary for computing 1/(0.5-k) value
* t0.w = final coverage value
*/
tmp0 = ts->tmp;
/* SUB t0.xy, texIn, (0.5, 0,5) */
tgsi_transform_op2_inst(ctx, TGSI_OPCODE_ADD,
TGSI_FILE_TEMPORARY, tmp0, TGSI_WRITEMASK_XY,
TGSI_FILE_INPUT, texIn,
TGSI_FILE_IMMEDIATE, imm, true);
/* DP2 t0.x, t0.xy, t0.xy; # t0.x = x^2 + y^2 */
tgsi_transform_op2_inst(ctx, TGSI_OPCODE_DP2,
TGSI_FILE_TEMPORARY, tmp0, TGSI_WRITEMASK_X,
TGSI_FILE_TEMPORARY, tmp0,
TGSI_FILE_TEMPORARY, tmp0, false);
/* SQRT t0.x, t0.x */
tgsi_transform_op1_inst(ctx, TGSI_OPCODE_SQRT,
TGSI_FILE_TEMPORARY, tmp0, TGSI_WRITEMASK_X,
TGSI_FILE_TEMPORARY, tmp0);
/* compute coverage factor = (0.5-d)/(0.5-k) */
/* SUB t0.w, 0.5, texIn.z; # t0.w = 0.5-k */
tgsi_transform_op2_swz_inst(ctx, TGSI_OPCODE_ADD,
TGSI_FILE_TEMPORARY, tmp0, TGSI_WRITEMASK_W,
TGSI_FILE_IMMEDIATE, imm, TGSI_SWIZZLE_X,
TGSI_FILE_INPUT, texIn, TGSI_SWIZZLE_Z, true);
/* SUB t0.y, 0.5, t0.x; # t0.y = 0.5-d */
tgsi_transform_op2_swz_inst(ctx, TGSI_OPCODE_ADD,
TGSI_FILE_TEMPORARY, tmp0, TGSI_WRITEMASK_Y,
TGSI_FILE_IMMEDIATE, imm, TGSI_SWIZZLE_X,
TGSI_FILE_TEMPORARY, tmp0, TGSI_SWIZZLE_X, true);
/* DIV t0.w, t0.y, t0.w; # coverage = (0.5-d)/(0.5-k) */
tgsi_transform_op2_swz_inst(ctx, TGSI_OPCODE_DIV,
TGSI_FILE_TEMPORARY, tmp0, TGSI_WRITEMASK_W,
TGSI_FILE_TEMPORARY, tmp0, TGSI_SWIZZLE_Y,
TGSI_FILE_TEMPORARY, tmp0, TGSI_SWIZZLE_W, false);
/* If the coverage value is negative, it means the fragment is outside
* the point's circular boundary. Kill it.
*/
/* KILL_IF tmp0.w; # if tmp0.w < 0 KILL */
tgsi_transform_kill_inst(ctx, TGSI_FILE_TEMPORARY, tmp0,
TGSI_SWIZZLE_W, FALSE);
/* If the distance is less than the threshold, the coverage/alpha value
* will be greater than one. Clamp to one here.
*/
/* MIN tmp0.w, tmp0.w, 1.0 */
tgsi_transform_op2_swz_inst(ctx, TGSI_OPCODE_MIN,
TGSI_FILE_TEMPORARY, tmp0, TGSI_WRITEMASK_W,
TGSI_FILE_TEMPORARY, tmp0, TGSI_SWIZZLE_W,
TGSI_FILE_IMMEDIATE, imm, TGSI_SWIZZLE_W, false);
}
/**
* TGSI instruction transform callback.
*/
static void
aa_inst(struct tgsi_transform_context *ctx,
struct tgsi_full_instruction *inst)
{
struct aa_transform_context *ts = aa_transform_context(ctx);
unsigned i;
/* Look for writes to color output reg and replace it with
* color temp reg.
*/
for (i = 0; i < inst->Instruction.NumDstRegs; i++) {
struct tgsi_full_dst_register *dst = &inst->Dst[i];
if (dst->Register.File == TGSI_FILE_OUTPUT &&
dst->Register.Index == ts->color_out) {
dst->Register.File = TGSI_FILE_TEMPORARY;
dst->Register.Index = ts->color_tmp;
}
}
ctx->emit_instruction(ctx, inst);
}
/**
* TGSI transform epilog callback.
*/
static void
aa_epilog(struct tgsi_transform_context *ctx)
{
struct aa_transform_context *ts = aa_transform_context(ctx);
/* add alpha modulation code at tail of program */
assert(ts->color_out != INVALID_INDEX);
assert(ts->color_tmp != INVALID_INDEX);
/* MOV output.color.xyz colorTmp */
tgsi_transform_op1_inst(ctx, TGSI_OPCODE_MOV,
TGSI_FILE_OUTPUT, ts->color_out,
TGSI_WRITEMASK_XYZ,
TGSI_FILE_TEMPORARY, ts->color_tmp);
/* MUL output.color.w colorTmp.w tmp0.w */
tgsi_transform_op2_inst(ctx, TGSI_OPCODE_MUL,
TGSI_FILE_OUTPUT, ts->color_out,
TGSI_WRITEMASK_W,
TGSI_FILE_TEMPORARY, ts->color_tmp,
TGSI_FILE_TEMPORARY, ts->tmp, false);
}
/**
* TGSI utility to transform a fragment shader to support antialiasing point.
*
* This utility accepts two inputs:
*\param tokens_in -- the original token string of the shader
*\param aa_point_coord_index -- the semantic index of the generic register
* that contains the point sprite texture coord
*
* For each fragment in the point, we compute the distance of the fragment
* from the point center using the point sprite texture coordinates.
* If the distance is greater than 0.5, we'll discard the fragment.
* Otherwise, we'll compute a coverage value which approximates how much
* of the fragment is inside the bounding circle of the point. If the distance
* is less than 'k', the coverage is 1. Else, the coverage is between 0 and 1.
* The final fragment color's alpha channel is then modulated by the coverage
* value.
*/
struct tgsi_token *
tgsi_add_aa_point(const struct tgsi_token *tokens_in,
const int aa_point_coord_index)
{
struct aa_transform_context transform;
const uint num_new_tokens = 200; /* should be enough */
const uint new_len = tgsi_num_tokens(tokens_in) + num_new_tokens;
struct tgsi_token *new_tokens;
/* allocate new tokens buffer */
new_tokens = tgsi_alloc_tokens(new_len);
if (!new_tokens)
return NULL;
/* setup transformation context */
memset(&transform, 0, sizeof(transform));
transform.base.transform_declaration = aa_decl;
transform.base.transform_instruction = aa_inst;
transform.base.transform_immediate = aa_immediate;
transform.base.prolog = aa_prolog;
transform.base.epilog = aa_epilog;
transform.tmp = INVALID_INDEX;
transform.color_out = INVALID_INDEX;
transform.color_tmp = INVALID_INDEX;
assert(aa_point_coord_index != -1);
transform.aa_point_coord_index = (unsigned)aa_point_coord_index;
transform.num_tmp = 0;
transform.num_imm = 0;
transform.num_input = 0;
/* transform the shader */
tgsi_transform_shader(tokens_in, new_tokens, new_len, &transform.base);
return new_tokens;
}