From: Andreas Faenger Date: Mon, 6 Jun 2011 07:13:16 +0000 (+0000) Subject: softpipe: Anisotropic filtering extension. X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=f4537f99cc83cb8133f66dc97c613e95dc0fe162;p=mesa.git softpipe: Anisotropic filtering extension. Reference implementation which produces high quality renderings. Based on Higher Quality Elliptical Weighted Avarage Filter (EWA). Signed-off-by: Brian Paul --- diff --git a/src/gallium/drivers/softpipe/sp_screen.c b/src/gallium/drivers/softpipe/sp_screen.c index 48aabc18da3..30f53a9e674 100644 --- a/src/gallium/drivers/softpipe/sp_screen.c +++ b/src/gallium/drivers/softpipe/sp_screen.c @@ -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: diff --git a/src/gallium/drivers/softpipe/sp_tex_sample.c b/src/gallium/drivers/softpipe/sp_tex_sample.c index 1446aee2aa4..90766f4119c 100644 --- a/src/gallium/drivers/softpipe/sp_tex_sample.c +++ b/src/gallium/drivers/softpipe/sp_tex_sample.c @@ -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; }