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softpipe: Anisotropic filtering extension.

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Reference implementation which produces high quality renderings.
Based on Higher Quality Elliptical Weighted Avarage Filter (EWA).

Signed-off-by: Brian Paul <brianp@vmware.com>
This commit is contained in:
Andreas Faenger
2011-06-06 07:13:16 +00:00
committed by Brian Paul
parent b438005d96
commit f4537f99cc
2 changed files with 336 additions and 6 deletions
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4
src/gallium/drivers/softpipe/sp_screen.c
View File

@@ -81,7 +81,7 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
case PIPE_CAP_SM3:
return 1;
case PIPE_CAP_ANISOTROPIC_FILTER:
return 0;
return 1;
case PIPE_CAP_POINT_SPRITE:
return 1;
case PIPE_CAP_MAX_RENDER_TARGETS:
@@ -161,7 +161,7 @@ softpipe_get_paramf(struct pipe_screen *screen, enum pipe_cap param)
case PIPE_CAP_MAX_POINT_WIDTH_AA:
return 255.0; /* arbitrary */
case PIPE_CAP_MAX_TEXTURE_ANISOTROPY:
return 16.0; /* not actually signficant at this time */
return 16.0;
case PIPE_CAP_MAX_TEXTURE_LOD_BIAS:
return 16.0; /* arbitrary */
default:

338
src/gallium/drivers/softpipe/sp_tex_sample.c
View File

@@ -1709,6 +1709,317 @@ mip_filter_none(struct tgsi_sampler *tgsi_sampler,
}
/* For anisotropic filtering */
#define WEIGHT_LUT_SIZE 1024
static float *weightLut = NULL;
/**
* Creates the look-up table used to speed-up EWA sampling
*/
static void
create_filter_table(void)
{
unsigned i;
if (!weightLut) {
weightLut = (float *) malloc(WEIGHT_LUT_SIZE * sizeof(float));
for (i = 0; i < WEIGHT_LUT_SIZE; ++i) {
float alpha = 2;
float r2 = (float) i / (float) (WEIGHT_LUT_SIZE - 1);
float weight = (float) exp(-alpha * r2);
weightLut[i] = weight;
}
}
}
/**
* Elliptical weighted average (EWA) filter for producing high quality
* anisotropic filtered results.
* Based on the Higher Quality Elliptical Weighted Avarage Filter
* published by Paul S. Heckbert in his Master's Thesis
* "Fundamentals of Texture Mapping and Image Warping" (1989)
*/
static void
img_filter_2d_ewa(struct tgsi_sampler *tgsi_sampler,
const float s[QUAD_SIZE],
const float t[QUAD_SIZE],
const float p[QUAD_SIZE],
const float c0[QUAD_SIZE],
enum tgsi_sampler_control control,
const float dudx, const float dvdx,
const float dudy, const float dvdy,
float rgba[NUM_CHANNELS][QUAD_SIZE])
{
const struct sp_sampler_variant *samp = sp_sampler_variant(tgsi_sampler);
const struct pipe_resource *texture = samp->view->texture;
unsigned level0 = samp->level > 0 ? samp->level : 0;
float scaling = 1.0 / (1 << level0);
int width = u_minify(texture->width0, level0);
int height = u_minify(texture->height0, level0);
float ux = dudx * scaling;
float vx = dvdx * scaling;
float uy = dudy * scaling;
float vy = dvdy * scaling;
/* compute ellipse coefficients to bound the region:
* A*x*x + B*x*y + C*y*y = F.
*/
float A = vx*vx+vy*vy+1;
float B = -2*(ux*vx+uy*vy);
float C = ux*ux+uy*uy+1;
float F = A*C-B*B/4.0;
/* check if it is an ellipse */
/* ASSERT(F > 0.0); */
/* Compute the ellipse's (u,v) bounding box in texture space */
float d = -B*B+4.0*C*A;
float box_u = 2.0 / d * sqrt(d*C*F); /* box_u -> half of bbox with */
float box_v = 2.0 / d * sqrt(A*d*F); /* box_v -> half of bbox height */
float rgba_temp[NUM_CHANNELS][QUAD_SIZE];
float s_buffer[QUAD_SIZE];
float t_buffer[QUAD_SIZE];
float weight_buffer[QUAD_SIZE];
unsigned buffer_next;
int j;
float den;// = 0.0F;
float ddq;
float U;// = u0 - tex_u;
int v;
/* Scale ellipse formula to directly index the Filter Lookup Table.
* i.e. scale so that F = WEIGHT_LUT_SIZE-1
*/
double formScale = (double) (WEIGHT_LUT_SIZE - 1) / F;
A *= formScale;
B *= formScale;
C *= formScale;
/* F *= formScale; */ /* no need to scale F as we don't use it below here */
/* For each quad, the du and dx values are the same and so the ellipse is
* also the same. Note that texel/image access can only be performed using
* a quad, i.e. it is not possible to get the pixel value for a single
* tex coord. In order to have a better performance, the access is buffered
* using the s_buffer/t_buffer and weight_buffer. Only when the buffer is full,
* then the pixel values are read from the image.
*/
ddq = 2 * A;
for (j = 0; j < QUAD_SIZE; j++) {
/* Heckbert MS thesis, p. 59; scan over the bounding box of the ellipse
* and incrementally update the value of Ax^2+Bxy*Cy^2; when this
* value, q, is less than F, we're inside the ellipse
*/
float tex_u=-0.5 + s[j] * texture->width0 * scaling;
float tex_v=-0.5 + t[j] * texture->height0 * scaling;
int u0 = floor(tex_u - box_u);
int u1 = ceil (tex_u + box_u);
int v0 = floor(tex_v - box_v);
int v1 = ceil (tex_v + box_v);
float num[4] = {0.0F, 0.0F, 0.0F, 0.0F};
buffer_next = 0;
den = 0;
U = u0 - tex_u;
for (v = v0; v <= v1; ++v) {
float V = v - tex_v;
float dq = A * (2 * U + 1) + B * V;
float q = (C * V + B * U) * V + A * U * U;
int u;
for (u = u0; u <= u1; ++u) {
/* Note that the ellipse has been pre-scaled so F = WEIGHT_LUT_SIZE - 1 */
if (q < WEIGHT_LUT_SIZE) {
/* as a LUT is used, q must never be negative;
* should not happen, though
*/
const int qClamped = q >= 0.0F ? q : 0;
float weight = weightLut[qClamped];
weight_buffer[buffer_next] = weight;
s_buffer[buffer_next] = u / ((float) width);
t_buffer[buffer_next] = v / ((float) height);
buffer_next++;
if (buffer_next == QUAD_SIZE) {
/* 4 texel coords are in the buffer -> read it now */
int jj;
/* it is assumed that samp->min_img_filter is set to
* img_filter_2d_nearest or one of the
* accelerated img_filter_2d_nearest_XXX functions.
*/
samp->min_img_filter(tgsi_sampler, s_buffer, t_buffer, p, NULL,
tgsi_sampler_lod_bias, rgba_temp);
for (jj = 0; jj < buffer_next; jj++) {
num[0] += weight_buffer[jj] * rgba_temp[0][jj];
num[1] += weight_buffer[jj] * rgba_temp[1][jj];
num[2] += weight_buffer[jj] * rgba_temp[2][jj];
num[3] += weight_buffer[jj] * rgba_temp[3][jj];
}
buffer_next = 0;
}
den += weight;
}
q += dq;
dq += ddq;
}
}
/* if the tex coord buffer contains unread values, we will read them now.
* Note that in most cases we have to read more pixel values than required,
* however, as the img_filter_2d_nearest function(s) does not have a count
* parameter, we need to read the whole quad and ignore the unused values
*/
if (buffer_next > 0) {
int jj;
/* it is assumed that samp->min_img_filter is set to
* img_filter_2d_nearest or one of the
* accelerated img_filter_2d_nearest_XXX functions.
*/
samp->min_img_filter(tgsi_sampler, s_buffer, t_buffer, p, NULL,
tgsi_sampler_lod_bias, rgba_temp);
for (jj = 0; jj < buffer_next; jj++) {
num[0] += weight_buffer[jj] * rgba_temp[0][jj];
num[1] += weight_buffer[jj] * rgba_temp[1][jj];
num[2] += weight_buffer[jj] * rgba_temp[2][jj];
num[3] += weight_buffer[jj] * rgba_temp[3][jj];
}
}
if (den <= 0.0F) {
/* Reaching this place would mean
* that no pixels intersected the ellipse.
* This should never happen because
* the filter we use always
* intersects at least one pixel.
*/
/*rgba[0]=0;
rgba[1]=0;
rgba[2]=0;
rgba[3]=0;*/
/* not enough pixels in resampling, resort to direct interpolation */
samp->min_img_filter(tgsi_sampler, s, t, p, NULL, tgsi_sampler_lod_bias, rgba_temp);
den = 1;
num[0] = rgba_temp[0][j];
num[1] = rgba_temp[1][j];
num[2] = rgba_temp[2][j];
num[3] = rgba_temp[3][j];
}
rgba[0][j] = num[0] / den;
rgba[1][j] = num[1] / den;
rgba[2][j] = num[2] / den;
rgba[3][j] = num[3] / den;
}
}
/**
* Sample 2D texture using an anisotropic filter.
*/
static void
mip_filter_linear_aniso(struct tgsi_sampler *tgsi_sampler,
const float s[QUAD_SIZE],
const float t[QUAD_SIZE],
const float p[QUAD_SIZE],
const float c0[QUAD_SIZE],
enum tgsi_sampler_control control,
float rgba[NUM_CHANNELS][QUAD_SIZE])
{
struct sp_sampler_variant *samp = sp_sampler_variant(tgsi_sampler);
const struct pipe_resource *texture = samp->view->texture;
int level0;
float lambda;
float lod[QUAD_SIZE];
float s_to_u = u_minify(texture->width0, samp->view->u.tex.first_level);
float t_to_v = u_minify(texture->height0, samp->view->u.tex.first_level);
float dudx = (s[QUAD_BOTTOM_RIGHT] - s[QUAD_BOTTOM_LEFT]) * s_to_u;
float dudy = (s[QUAD_TOP_LEFT] - s[QUAD_BOTTOM_LEFT]) * s_to_u;
float dvdx = (t[QUAD_BOTTOM_RIGHT] - t[QUAD_BOTTOM_LEFT]) * t_to_v;
float dvdy = (t[QUAD_TOP_LEFT] - t[QUAD_BOTTOM_LEFT]) * t_to_v;
if (control == tgsi_sampler_lod_bias) {
/* note: instead of working with Px and Py, we will use the
* squared length instead, to avoid sqrt.
*/
float Px2 = dudx * dudx + dvdx * dvdx;
float Py2 = dudy * dudy + dvdy * dvdy;
float Pmax2;
float Pmin2;
float e;
const float maxEccentricity = samp->sampler->max_anisotropy * samp->sampler->max_anisotropy;
if (Px2 < Py2) {
Pmax2 = Py2;
Pmin2 = Px2;
}
else {
Pmax2 = Px2;
Pmin2 = Py2;
}
/* if the eccentricity of the ellipse is too big, scale up the shorter
* of the two vectors to limit the maximum amount of work per pixel
*/
e = Pmax2 / Pmin2;
if (e > maxEccentricity) {
/* float s=e / maxEccentricity;
minor[0] *= s;
minor[1] *= s;
Pmin2 *= s; */
Pmin2 = Pmax2 / maxEccentricity;
}
/* note: we need to have Pmin=sqrt(Pmin2) here, but we can avoid
* this since 0.5*log(x) = log(sqrt(x))
*/
lambda = 0.5 * util_fast_log2(Pmin2) + samp->sampler->lod_bias;
compute_lod(samp->sampler, lambda, c0, lod);
}
else {
assert(control == tgsi_sampler_lod_explicit);
memcpy(lod, c0, sizeof(lod));
}
/* XXX: Take into account all lod values.
*/
lambda = lod[0];
level0 = samp->view->u.tex.first_level + (int)lambda;
/* If the ellipse covers the whole image, we can
* simply return the average of the whole image.
*/
if (level0 >= texture->last_level) {
samp->level = texture->last_level;
samp->min_img_filter(tgsi_sampler, s, t, p, NULL, tgsi_sampler_lod_bias, rgba);
}
else {
/* don't bother interpolating between multiple LODs; it doesn't
* seem to be worth the extra running time.
*/
samp->level = level0;
img_filter_2d_ewa(tgsi_sampler, s, t, p, NULL, tgsi_sampler_lod_bias,
dudx, dvdx, dudy, dvdy, rgba);
}
if (DEBUG_TEX) {
print_sample(__FUNCTION__, rgba);
}
}
/**
* Specialized version of mip_filter_linear with hard-wired calls to
@@ -2316,14 +2627,33 @@ sp_create_sampler_variant( const struct pipe_sampler_state *sampler,
sampler->normalized_coords &&
sampler->wrap_s == PIPE_TEX_WRAP_REPEAT &&
sampler->wrap_t == PIPE_TEX_WRAP_REPEAT &&
sampler->min_img_filter == PIPE_TEX_FILTER_LINEAR)
{
sampler->min_img_filter == PIPE_TEX_FILTER_LINEAR) {
samp->mip_filter = mip_filter_linear_2d_linear_repeat_POT;
}
else
{
else {
samp->mip_filter = mip_filter_linear;
}
/* Anisotropic filtering extension. */
if (sampler->max_anisotropy > 1) {
samp->mip_filter = mip_filter_linear_aniso;
/* Override min_img_filter:
* min_img_filter needs to be set to NEAREST since we need to access
* each texture pixel as it is and weight it later; using linear
* filters will have incorrect results.
* By setting the filter to NEAREST here, we can avoid calling the
* generic img_filter_2d_nearest in the anisotropic filter function,
* making it possible to use one of the accelerated implementations
*/
samp->min_img_filter = get_img_filter(key, PIPE_TEX_FILTER_NEAREST, sampler);
/* on first access create the lookup table containing the filter weights. */
if (!weightLut) {
create_filter_table();
}
}
break;
}