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mpv/video/out/opengl/video_shaders.c
Niklas Haas d8a3b10f45
vo_opengl: add new HDR tone mapping algorithm 
I call it `mobius` because apparently the form f(x) = (cx+a)/(dx+b) is
called a Möbius transform, which is the algorithm this is based on. In
the extremes it becomes `reinhard` (param=0.0 and `clip` (param=1.0),
smoothly transitioning between the two depending on the parameter.

This is a useful tone mapping algorithm since the tunable mobius
transform allows the user to decide the trade-off between color accuracy
and detail preservation on a continuous scale. The default of 0.3 is
already far more accurate than `reinhard` while also being reasonably
good at preserving highlights, without suffering from the overall
brightness drop and color distortion of `hable`.

For these reasons, make this the new default. Also expand and improve
the documentation for these tone mapping functions.
2017-06-09 11:27:28 +01:00

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/*
* This file is part of mpv.
*
* mpv is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* mpv is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <math.h>
#include "video_shaders.h"
#include "video.h"
#define GLSL(x) gl_sc_add(sc, #x "\n");
#define GLSLF(...) gl_sc_addf(sc, __VA_ARGS__)
#define GLSLH(x) gl_sc_hadd(sc, #x "\n");
#define GLSLHF(...) gl_sc_haddf(sc, __VA_ARGS__)
// Set up shared/commonly used variables and macros
void sampler_prelude(struct gl_shader_cache *sc, int tex_num)
{
GLSLF("#undef tex\n");
GLSLF("#define tex texture%d\n", tex_num);
GLSLF("vec2 pos = texcoord%d;\n", tex_num);
GLSLF("vec2 size = texture_size%d;\n", tex_num);
GLSLF("vec2 pt = pixel_size%d;\n", tex_num);
}
static void pass_sample_separated_get_weights(struct gl_shader_cache *sc,
struct scaler *scaler)
{
gl_sc_uniform_tex(sc, "lut", scaler->gl_target, scaler->gl_lut);
// Define a new variable to cache the corrected fcoord.
GLSLF("float fcoord_lut = LUT_POS(fcoord, %d.0);\n", scaler->lut_size);
int N = scaler->kernel->size;
if (N == 2) {
GLSL(vec2 c1 = texture(lut, vec2(0.5, fcoord_lut)).rg;)
GLSL(float weights[2] = float[](c1.r, c1.g);)
} else if (N == 6) {
GLSL(vec4 c1 = texture(lut, vec2(0.25, fcoord_lut));)
GLSL(vec4 c2 = texture(lut, vec2(0.75, fcoord_lut));)
GLSL(float weights[6] = float[](c1.r, c1.g, c1.b, c2.r, c2.g, c2.b);)
} else {
GLSLF("float weights[%d];\n", N);
for (int n = 0; n < N / 4; n++) {
GLSLF("c = texture(lut, vec2(1.0 / %d.0 + %d.0 / %d.0, fcoord_lut));\n",
N / 2, n, N / 4);
GLSLF("weights[%d] = c.r;\n", n * 4 + 0);
GLSLF("weights[%d] = c.g;\n", n * 4 + 1);
GLSLF("weights[%d] = c.b;\n", n * 4 + 2);
GLSLF("weights[%d] = c.a;\n", n * 4 + 3);
}
}
}
// Handle a single pass (either vertical or horizontal). The direction is given
// by the vector (d_x, d_y). If the vector is 0, then planar interpolation is
// used instead (samples from texture0 through textureN)
void pass_sample_separated_gen(struct gl_shader_cache *sc, struct scaler *scaler,
int d_x, int d_y)
{
int N = scaler->kernel->size;
bool use_ar = scaler->conf.antiring > 0;
bool planar = d_x == 0 && d_y == 0;
GLSL(color = vec4(0.0);)
GLSLF("{\n");
if (!planar) {
GLSLF("vec2 dir = vec2(%d.0, %d.0);\n", d_x, d_y);
GLSL(pt *= dir;)
GLSL(float fcoord = dot(fract(pos * size - vec2(0.5)), dir);)
GLSLF("vec2 base = pos - fcoord * pt - pt * vec2(%d.0);\n", N / 2 - 1);
}
GLSL(vec4 c;)
if (use_ar) {
GLSL(vec4 hi = vec4(0.0);)
GLSL(vec4 lo = vec4(1.0);)
}
pass_sample_separated_get_weights(sc, scaler);
GLSLF("// scaler samples\n");
for (int n = 0; n < N; n++) {
if (planar) {
GLSLF("c = texture(texture%d, texcoord%d);\n", n, n);
} else {
GLSLF("c = texture(tex, base + pt * vec2(%d.0));\n", n);
}
GLSLF("color += vec4(weights[%d]) * c;\n", n);
if (use_ar && (n == N/2-1 || n == N/2)) {
GLSL(lo = min(lo, c);)
GLSL(hi = max(hi, c);)
}
}
if (use_ar)
GLSLF("color = mix(color, clamp(color, lo, hi), %f);\n",
scaler->conf.antiring);
GLSLF("}\n");
}
void pass_sample_polar(struct gl_shader_cache *sc, struct scaler *scaler)
{
double radius = scaler->kernel->f.radius * scaler->kernel->filter_scale;
int bound = ceil(radius);
bool use_ar = scaler->conf.antiring > 0;
GLSL(color = vec4(0.0);)
GLSLF("{\n");
GLSL(vec2 fcoord = fract(pos * size - vec2(0.5));)
GLSL(vec2 base = pos - fcoord * pt;)
GLSL(vec4 c;)
GLSLF("float w, d, wsum = 0.0;\n");
if (use_ar) {
GLSL(vec4 lo = vec4(1.0);)
GLSL(vec4 hi = vec4(0.0);)
}
gl_sc_uniform_tex(sc, "lut", scaler->gl_target, scaler->gl_lut);
GLSLF("// scaler samples\n");
for (int y = 1-bound; y <= bound; y++) {
for (int x = 1-bound; x <= bound; x++) {
// Since we can't know the subpixel position in advance, assume a
// worst case scenario
int yy = y > 0 ? y-1 : y;
int xx = x > 0 ? x-1 : x;
double dmax = sqrt(xx*xx + yy*yy);
// Skip samples definitely outside the radius
if (dmax >= radius)
continue;
GLSLF("d = length(vec2(%d.0, %d.0) - fcoord)/%f;\n", x, y, radius);
// Check for samples that might be skippable
if (dmax >= radius - M_SQRT2)
GLSLF("if (d < 1.0) {\n");
if (scaler->gl_target == GL_TEXTURE_1D) {
GLSLF("w = texture1D(lut, LUT_POS(d, %d.0)).r;\n",
scaler->lut_size);
} else {
GLSLF("w = texture(lut, vec2(0.5, LUT_POS(d, %d.0))).r;\n",
scaler->lut_size);
}
GLSL(wsum += w;)
GLSLF("c = texture(tex, base + pt * vec2(%d.0, %d.0));\n", x, y);
GLSL(color += vec4(w) * c;)
if (use_ar && x >= 0 && y >= 0 && x <= 1 && y <= 1) {
GLSL(lo = min(lo, c);)
GLSL(hi = max(hi, c);)
}
if (dmax >= radius - M_SQRT2)
GLSLF("}\n");
}
}
GLSL(color = color / vec4(wsum);)
if (use_ar)
GLSLF("color = mix(color, clamp(color, lo, hi), %f);\n",
scaler->conf.antiring);
GLSLF("}\n");
}
static void bicubic_calcweights(struct gl_shader_cache *sc, const char *t, const char *s)
{
// Explanation of how bicubic scaling with only 4 texel fetches is done:
// http://www.mate.tue.nl/mate/pdfs/10318.pdf
// 'Efficient GPU-Based Texture Interpolation using Uniform B-Splines'
// Explanation why this algorithm normally always blurs, even with unit
// scaling:
// http://bigwww.epfl.ch/preprints/ruijters1001p.pdf
// 'GPU Prefilter for Accurate Cubic B-spline Interpolation'
GLSLF("vec4 %s = vec4(-0.5, 0.1666, 0.3333, -0.3333) * %s"
" + vec4(1, 0, -0.5, 0.5);\n", t, s);
GLSLF("%s = %s * %s + vec4(0, 0, -0.5, 0.5);\n", t, t, s);
GLSLF("%s = %s * %s + vec4(-0.6666, 0, 0.8333, 0.1666);\n", t, t, s);
GLSLF("%s.xy *= vec2(1, 1) / vec2(%s.z, %s.w);\n", t, t, t);
GLSLF("%s.xy += vec2(1.0 + %s, 1.0 - %s);\n", t, s, s);
}
void pass_sample_bicubic_fast(struct gl_shader_cache *sc)
{
GLSLF("{\n");
GLSL(vec2 fcoord = fract(pos * size + vec2(0.5, 0.5));)
bicubic_calcweights(sc, "parmx", "fcoord.x");
bicubic_calcweights(sc, "parmy", "fcoord.y");
GLSL(vec4 cdelta;)
GLSL(cdelta.xz = parmx.rg * vec2(-pt.x, pt.x);)
GLSL(cdelta.yw = parmy.rg * vec2(-pt.y, pt.y);)
// first y-interpolation
GLSL(vec4 ar = texture(tex, pos + cdelta.xy);)
GLSL(vec4 ag = texture(tex, pos + cdelta.xw);)
GLSL(vec4 ab = mix(ag, ar, parmy.b);)
// second y-interpolation
GLSL(vec4 br = texture(tex, pos + cdelta.zy);)
GLSL(vec4 bg = texture(tex, pos + cdelta.zw);)
GLSL(vec4 aa = mix(bg, br, parmy.b);)
// x-interpolation
GLSL(color = mix(aa, ab, parmx.b);)
GLSLF("}\n");
}
void pass_sample_oversample(struct gl_shader_cache *sc, struct scaler *scaler,
int w, int h)
{
GLSLF("{\n");
GLSL(vec2 pos = pos + vec2(0.5) * pt;) // round to nearest
GLSL(vec2 fcoord = fract(pos * size - vec2(0.5));)
// Determine the mixing coefficient vector
gl_sc_uniform_vec2(sc, "output_size", (float[2]){w, h});
GLSL(vec2 coeff = fcoord * output_size/size;)
float threshold = scaler->conf.kernel.params[0];
threshold = isnan(threshold) ? 0.0 : threshold;
GLSLF("coeff = (coeff - %f) / %f;\n", threshold, 1.0 - 2 * threshold);
GLSL(coeff = clamp(coeff, 0.0, 1.0);)
// Compute the right blend of colors
GLSL(color = texture(tex, pos + pt * (coeff - fcoord));)
GLSLF("}\n");
}
// Common constants for SMPTE ST.2084 (HDR)
static const float HDR_M1 = 2610./4096 * 1./4,
HDR_M2 = 2523./4096 * 128,
HDR_C1 = 3424./4096,
HDR_C2 = 2413./4096 * 32,
HDR_C3 = 2392./4096 * 32;
// Common constants for ARIB STD-B67 (Hybrid Log-gamma)
static const float B67_A = 0.17883277,
B67_B = 0.28466892,
B67_C = 0.55991073;
// Common constants for Panasonic V-Log
static const float VLOG_B = 0.00873,
VLOG_C = 0.241514,
VLOG_D = 0.598206,
VLOG_R = 46.085527; // nominal peak
// Linearize (expand), given a TRC as input. This corresponds to the EOTF
// in ITU-R terminology.
void pass_linearize(struct gl_shader_cache *sc, enum mp_csp_trc trc)
{
if (trc == MP_CSP_TRC_LINEAR)
return;
// Note that this clamp may technically violate the definition of
// ITU-R BT.2100, which allows for sub-blacks and super-whites to be
// displayed on the display where such would be possible. That said, the
// problem is that not all gamma curves are well-defined on the values
// outside this range, so we ignore it and just clip anyway for sanity.
GLSL(color.rgb = clamp(color.rgb, 0.0, 1.0);)
switch (trc) {
case MP_CSP_TRC_SRGB:
GLSL(color.rgb = mix(color.rgb / vec3(12.92),
pow((color.rgb + vec3(0.055))/vec3(1.055), vec3(2.4)),
lessThan(vec3(0.04045), color.rgb));)
break;
case MP_CSP_TRC_BT_1886:
// We don't have an actual black point, so we assume a perfect display
GLSL(color.rgb = pow(color.rgb, vec3(2.4));)
break;
case MP_CSP_TRC_GAMMA18:
GLSL(color.rgb = pow(color.rgb, vec3(1.8));)
break;
case MP_CSP_TRC_GAMMA22:
GLSL(color.rgb = pow(color.rgb, vec3(2.2));)
break;
case MP_CSP_TRC_GAMMA28:
GLSL(color.rgb = pow(color.rgb, vec3(2.8));)
break;
case MP_CSP_TRC_PRO_PHOTO:
GLSL(color.rgb = mix(color.rgb / vec3(16.0),
pow(color.rgb, vec3(1.8)),
lessThan(vec3(0.03125), color.rgb));)
break;
case MP_CSP_TRC_SMPTE_ST2084:
GLSLF("color.rgb = pow(color.rgb, vec3(1.0/%f));\n", HDR_M2);
GLSLF("color.rgb = max(color.rgb - vec3(%f), vec3(0.0)) \n"
" / (vec3(%f) - vec3(%f) * color.rgb);\n",
HDR_C1, HDR_C2, HDR_C3);
GLSLF("color.rgb = pow(color.rgb, vec3(1.0/%f));\n", HDR_M1);
break;
case MP_CSP_TRC_ARIB_STD_B67:
GLSLF("color.rgb = mix(vec3(4.0) * color.rgb * color.rgb,\n"
" exp((color.rgb - vec3(%f)) / vec3(%f)) + vec3(%f),\n"
" lessThan(vec3(0.5), color.rgb));\n",
B67_C, B67_A, B67_B);
// Since the ARIB function's signal value of 1.0 corresponds to
// a peak of 12.0, we need to renormalize to prevent GL textures
// from clipping. (In general, mpv's internal conversions always
// assume 1.0 is the maximum brightness, not the reference peak)
GLSL(color.rgb /= vec3(12.0);)
break;
case MP_CSP_TRC_V_LOG:
GLSLF("color.rgb = mix((color.rgb - vec3(0.125)) / vec3(5.6), \n"
" pow(vec3(10.0), (color.rgb - vec3(%f)) / vec3(%f)) \n"
" - vec3(%f), \n"
" lessThanEqual(vec3(0.181), color.rgb)); \n",
VLOG_D, VLOG_C, VLOG_B);
// Same deal as with the B67 function, renormalize to texture range
GLSLF("color.rgb /= vec3(%f);\n", VLOG_R);
GLSL(color.rgb = clamp(color.rgb, 0.0, 1.0);)
break;
default:
abort();
}
}
// Delinearize (compress), given a TRC as output. This corresponds to the
// inverse EOTF (not the OETF) in ITU-R terminology.
void pass_delinearize(struct gl_shader_cache *sc, enum mp_csp_trc trc)
{
if (trc == MP_CSP_TRC_LINEAR)
return;
GLSL(color.rgb = clamp(color.rgb, 0.0, 1.0);)
switch (trc) {
case MP_CSP_TRC_SRGB:
GLSL(color.rgb = mix(color.rgb * vec3(12.92),
vec3(1.055) * pow(color.rgb, vec3(1.0/2.4))
- vec3(0.055),
lessThanEqual(vec3(0.0031308), color.rgb));)
break;
case MP_CSP_TRC_BT_1886:
GLSL(color.rgb = pow(color.rgb, vec3(1.0/2.4));)
break;
case MP_CSP_TRC_GAMMA18:
GLSL(color.rgb = pow(color.rgb, vec3(1.0/1.8));)
break;
case MP_CSP_TRC_GAMMA22:
GLSL(color.rgb = pow(color.rgb, vec3(1.0/2.2));)
break;
case MP_CSP_TRC_GAMMA28:
GLSL(color.rgb = pow(color.rgb, vec3(1.0/2.8));)
break;
case MP_CSP_TRC_PRO_PHOTO:
GLSL(color.rgb = mix(color.rgb * vec3(16.0),
pow(color.rgb, vec3(1.0/1.8)),
lessThanEqual(vec3(0.001953), color.rgb));)
break;
case MP_CSP_TRC_SMPTE_ST2084:
GLSLF("color.rgb = pow(color.rgb, vec3(%f));\n", HDR_M1);
GLSLF("color.rgb = (vec3(%f) + vec3(%f) * color.rgb) \n"
" / (vec3(1.0) + vec3(%f) * color.rgb);\n",
HDR_C1, HDR_C2, HDR_C3);
GLSLF("color.rgb = pow(color.rgb, vec3(%f));\n", HDR_M2);
break;
case MP_CSP_TRC_ARIB_STD_B67:
GLSL(color.rgb *= vec3(12.0);)
GLSLF("color.rgb = mix(vec3(0.5) * sqrt(color.rgb),\n"
" vec3(%f) * log(color.rgb - vec3(%f)) + vec3(%f),\n"
" lessThan(vec3(1.0), color.rgb));\n",
B67_A, B67_B, B67_C);
break;
case MP_CSP_TRC_V_LOG:
GLSLF("color.rgb *= vec3(%f);\n", VLOG_R);
GLSLF("color.rgb = mix(vec3(5.6) * color.rgb + vec3(0.125), \n"
" vec3(%f) * log(color.rgb + vec3(%f)) \n"
" + vec3(%f), \n"
" lessThanEqual(vec3(0.01), color.rgb)); \n",
VLOG_C / M_LN10, VLOG_B, VLOG_D);
break;
default:
abort();
}
}
// Tone map from a known peak brightness to the range [0,1]
static void pass_tone_map(struct gl_shader_cache *sc, float ref_peak,
enum tone_mapping algo, float param)
{
GLSLF("// HDR tone mapping\n");
switch (algo) {
case TONE_MAPPING_CLIP:
GLSL(color.rgb = clamp(color.rgb, 0.0, 1.0);)
break;
case TONE_MAPPING_MOBIUS: {
float j = isnan(param) ? 0.3 : param;
// solve for M(j) = j; M(ref_peak) = 1.0; M'(j) = 1.0
// where M(x) = scale * (x+a)/(x+b)
float a = -j*j * (ref_peak - 1) / (j*j - 2*j + ref_peak),
b = (j*j - 2*j*ref_peak + ref_peak) / (ref_peak - 1);
GLSLF("color.rgb = mix(vec3(%f) * (color.rgb + vec3(%f))\n"
" / (color.rgb + vec3(%f)),\n"
" color.rgb,\n"
" lessThanEqual(color.rgb, vec3(%f)));\n",
(b*b + 2*b*j + j*j) / (b - a), a, b, j);
break;
}
case TONE_MAPPING_REINHARD: {
float contrast = isnan(param) ? 0.5 : param,
offset = (1.0 - contrast) / contrast;
GLSLF("color.rgb = color.rgb / (color.rgb + vec3(%f));\n", offset);
GLSLF("color.rgb *= vec3(%f);\n", (ref_peak + offset) / ref_peak);
break;
}
case TONE_MAPPING_HABLE: {
float A = 0.15, B = 0.50, C = 0.10, D = 0.20, E = 0.02, F = 0.30;
GLSLHF("vec3 hable(vec3 x) {\n");
GLSLHF("return ((x * (%f*x + %f)+%f)/(x * (%f*x + %f) + %f)) - %f;\n",
A, C*B, D*E, A, B, D*F, E/F);
GLSLHF("}\n");
GLSLF("color.rgb = hable(color.rgb) / hable(vec3(%f));\n", ref_peak);
break;
}
case TONE_MAPPING_GAMMA: {
float gamma = isnan(param) ? 1.8 : param;
GLSLF("color.rgb = pow(color.rgb / vec3(%f), vec3(%f));\n",
ref_peak, 1.0/gamma);
break;
}
case TONE_MAPPING_LINEAR: {
float coeff = isnan(param) ? 1.0 : param;
GLSLF("color.rgb = vec3(%f) * color.rgb;\n", coeff / ref_peak);
break;
}
default:
abort();
}
}
// Map colors from one source space to another. These source spaces
// must be known (i.e. not MP_CSP_*_AUTO), as this function won't perform
// any auto-guessing.
void pass_color_map(struct gl_shader_cache *sc,
struct mp_colorspace src, struct mp_colorspace dst,
enum tone_mapping algo, float tone_mapping_param)
{
GLSLF("// color mapping\n");
// All operations from here on require linear light as a starting point,
// so we linearize even if src.gamma == dst.gamma when one of the other
// operations needs it
bool need_gamma = src.gamma != dst.gamma ||
src.primaries != dst.primaries ||
src.nom_peak != dst.nom_peak ||
src.sig_peak > dst.nom_peak;
if (need_gamma)
pass_linearize(sc, src.gamma);
// NOTE: When src.gamma = MP_CSP_TRC_ARIB_STD_B67, we would technically
// need to apply the reference OOTF as part of the EOTF (which is what we
// implement with pass_linearize), since HLG considers OOTF to be part of
// the display's EOTF (as opposed to the camera's OETF). But since this is
// stupid, complicated, arbitrary, and more importantly depends on the
// target display's signal peak (which is != the nom_peak in the case of
// HDR displays, and mpv already has enough target-specific display
// options), we just ignore its implementation entirely. (Plus, it doesn't
// even really make sense with tone mapping to begin with.) But just in
// case somebody ends up complaining about HLG looking different from a
// reference HLG display, this comment might be why.
// Stretch the signal value to renormalize to the dst nominal peak
if (src.nom_peak != dst.nom_peak)
GLSLF("color.rgb *= vec3(%f);\n", src.nom_peak / dst.nom_peak);
// Tone map to prevent clipping when the source signal peak exceeds the
// encodable range.
if (src.sig_peak > dst.nom_peak)
pass_tone_map(sc, src.sig_peak / dst.nom_peak, algo, tone_mapping_param);
// Adapt to the right colorspace if necessary
if (src.primaries != dst.primaries) {
struct mp_csp_primaries csp_src = mp_get_csp_primaries(src.primaries),
csp_dst = mp_get_csp_primaries(dst.primaries);
float m[3][3] = {{0}};
mp_get_cms_matrix(csp_src, csp_dst, MP_INTENT_RELATIVE_COLORIMETRIC, m);
gl_sc_uniform_mat3(sc, "cms_matrix", true, &m[0][0]);
GLSL(color.rgb = cms_matrix * color.rgb;)
}
if (need_gamma)
pass_delinearize(sc, dst.gamma);
}
// Wide usage friendly PRNG, shamelessly stolen from a GLSL tricks forum post.
// Obtain random numbers by calling rand(h), followed by h = permute(h) to
// update the state. Assumes the texture was hooked.
static void prng_init(struct gl_shader_cache *sc, AVLFG *lfg)
{
GLSLH(float mod289(float x) { return x - floor(x / 289.0) * 289.0; })
GLSLH(float permute(float x) { return mod289((34.0*x + 1.0) * x); })
GLSLH(float rand(float x) { return fract(x / 41.0); })
// Initialize the PRNG by hashing the position + a random uniform
GLSL(vec3 _m = vec3(HOOKED_pos, random) + vec3(1.0);)
GLSL(float h = permute(permute(permute(_m.x)+_m.y)+_m.z);)
gl_sc_uniform_f(sc, "random", (double)av_lfg_get(lfg) / UINT32_MAX);
}
struct deband_opts {
int enabled;
int iterations;
float threshold;
float range;
float grain;
};
const struct deband_opts deband_opts_def = {
.iterations = 1,
.threshold = 64.0,
.range = 16.0,
.grain = 48.0,
};
#define OPT_BASE_STRUCT struct deband_opts
const struct m_sub_options deband_conf = {
.opts = (const m_option_t[]) {
OPT_INTRANGE("iterations", iterations, 0, 1, 16),
OPT_FLOATRANGE("threshold", threshold, 0, 0.0, 4096.0),
OPT_FLOATRANGE("range", range, 0, 1.0, 64.0),
OPT_FLOATRANGE("grain", grain, 0, 0.0, 4096.0),
{0}
},
.size = sizeof(struct deband_opts),
.defaults = &deband_opts_def,
};
// Stochastically sample a debanded result from a hooked texture.
void pass_sample_deband(struct gl_shader_cache *sc, struct deband_opts *opts,
AVLFG *lfg)
{
// Initialize the PRNG
GLSLF("{\n");
prng_init(sc, lfg);
// Helper: Compute a stochastic approximation of the avg color around a
// pixel
GLSLHF("vec4 average(float range, inout float h) {\n");
// Compute a random rangle and distance
GLSLH(float dist = rand(h) * range; h = permute(h);)
GLSLH(float dir = rand(h) * 6.2831853; h = permute(h);)
GLSLH(vec2 o = dist * vec2(cos(dir), sin(dir));)
// Sample at quarter-turn intervals around the source pixel
GLSLH(vec4 ref[4];)
GLSLH(ref[0] = HOOKED_texOff(vec2( o.x, o.y));)
GLSLH(ref[1] = HOOKED_texOff(vec2(-o.y, o.x));)
GLSLH(ref[2] = HOOKED_texOff(vec2(-o.x, -o.y));)
GLSLH(ref[3] = HOOKED_texOff(vec2( o.y, -o.x));)
// Return the (normalized) average
GLSLH(return (ref[0] + ref[1] + ref[2] + ref[3])/4.0;)
GLSLHF("}\n");
// Sample the source pixel
GLSL(color = HOOKED_tex(HOOKED_pos);)
GLSLF("vec4 avg, diff;\n");
for (int i = 1; i <= opts->iterations; i++) {
// Sample the average pixel and use it instead of the original if
// the difference is below the given threshold
GLSLF("avg = average(%f, h);\n", i * opts->range);
GLSL(diff = abs(color - avg);)
GLSLF("color = mix(avg, color, greaterThan(diff, vec4(%f)));\n",
opts->threshold / (i * 16384.0));
}
// Add some random noise to smooth out residual differences
GLSL(vec3 noise;)
GLSL(noise.x = rand(h); h = permute(h);)
GLSL(noise.y = rand(h); h = permute(h);)
GLSL(noise.z = rand(h); h = permute(h);)
GLSLF("color.xyz += %f * (noise - vec3(0.5));\n", opts->grain/8192.0);
GLSLF("}\n");
}
// Assumes the texture was hooked
void pass_sample_unsharp(struct gl_shader_cache *sc, float param) {
GLSLF("// unsharp\n");
GLSLF("{\n");
GLSL(float st1 = 1.2;)
GLSL(vec4 p = HOOKED_tex(HOOKED_pos);)
GLSL(vec4 sum1 = HOOKED_texOff(st1 * vec2(+1, +1))
+ HOOKED_texOff(st1 * vec2(+1, -1))
+ HOOKED_texOff(st1 * vec2(-1, +1))
+ HOOKED_texOff(st1 * vec2(-1, -1));)
GLSL(float st2 = 1.5;)
GLSL(vec4 sum2 = HOOKED_texOff(st2 * vec2(+1, 0))
+ HOOKED_texOff(st2 * vec2( 0, +1))
+ HOOKED_texOff(st2 * vec2(-1, 0))
+ HOOKED_texOff(st2 * vec2( 0, -1));)
GLSL(vec4 t = p * 0.859375 + sum2 * -0.1171875 + sum1 * -0.09765625;)
GLSLF("color = p + t * %f;\n", param);
GLSLF("}\n");
}
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