From 77d0c7ac9e3ebe1cecaf0c84e1501d3b6459055f Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 15 Jun 2019 14:21:53 +0300
Subject: [PATCH] Add a film grain postprocessor

---
 data/filmgrain.glsl  |  17 +++++
 source/filmgrain.cpp | 156 +++++++++++++++++++++++++++++++++++++++++++
 source/filmgrain.h   |  63 +++++++++++++++++
 source/launcher.cpp  |   2 +
 4 files changed, 238 insertions(+)
 create mode 100644 data/filmgrain.glsl
 create mode 100644 source/filmgrain.cpp
 create mode 100644 source/filmgrain.h

diff --git a/data/filmgrain.glsl b/data/filmgrain.glsl
new file mode 100644
index 0000000..9ae3d8f
--- /dev/null
+++ b/data/filmgrain.glsl
@@ -0,0 +1,17 @@
+import postprocess;
+
+uniform sampler2DArray grain;
+uniform GrainParams
+{
+	float coarseness;
+	float strength;
+};
+uniform int grain_layer;
+
+#pragma MSP stage(fragment)
+void main()
+{
+	vec3 gcoord = vec3(gl_FragCoord.xy/textureSize(grain, 0).xy/coarseness, grain_layer);
+	vec4 incoming = texture(source, texcoord);
+	frag_color = vec4(incoming.rgb*mix(1.0, texture(grain, gcoord).r, strength), incoming.a);
+}
diff --git a/source/filmgrain.cpp b/source/filmgrain.cpp
new file mode 100644
index 0000000..151daf5
--- /dev/null
+++ b/source/filmgrain.cpp
@@ -0,0 +1,156 @@
+#include <random>
+#include <msp/gl/renderer.h>
+#include <msp/gl/texture2d.h>
+#include "filmgrain.h"
+#include "resources.h"
+
+using namespace std;
+
+namespace Msp {
+namespace DemoScene {
+
+FilmGrain::FilmGrain(unsigned s, unsigned l):
+	mesh(get_fullscreen_quad()),
+	shprog(Resources::get_builtins().get<GL::Program>("filmgrain.glsl")),
+	size(s),
+	layers(l),
+	current_layer(0)
+{
+	grain.set_min_filter(GL::LINEAR);
+	grain.set_mag_filter(GL::LINEAR);
+	grain.set_wrap(GL::REPEAT);
+	grain.storage(GL::R8, size, size, layers, 1);
+
+	generate_grain();
+
+	texturing.attach(1, grain);
+	shdata.uniform("grain", 1);
+
+	set_coarseness(2.0f);
+	set_strength(0.1f);
+}
+
+void FilmGrain::generate_grain()
+{
+	UInt8 *data = new UInt8[size*size*layers];
+
+	unsigned noise_size = size/2;
+	UInt8 *noise = new UInt8[noise_size*noise_size];
+	Int16 *dbuf = new Int16[3*noise_size*noise_size];
+	minstd_rand random;
+
+	for(unsigned i=0; i<layers; ++i)
+	{
+		for(unsigned j=0; j<noise_size*noise_size; ++j)
+			noise[j] = random();
+
+		bicubic2x(noise, data+i*size*size, dbuf);
+	}
+
+	delete[] noise;
+	delete[] dbuf;
+
+	grain.image(0, GL::RED, GL::UNSIGNED_BYTE, data);
+	delete[] data;
+}
+
+void FilmGrain::bicubic2x(const UInt8 *src, UInt8 *target, Int16 *dbuf)
+{
+	unsigned src_size = size/2;
+
+	// dx and dy will have an implicit scaling factor of 2
+	Int16 *dx = dbuf;
+	Int16 *dy = dbuf+src_size*src_size;
+	for(unsigned y=0; y<src_size; ++y)
+		for(unsigned x=0; x<src_size; ++x)
+		{
+			unsigned i = x+y*src_size;
+			dx[i] = src[(x+1)%src_size + y*src_size] - src[(x+src_size-1)%src_size + y*src_size];
+			dy[i] = src[x + (y+1)%src_size*src_size] - src[x + (y+src_size-1)%src_size*src_size];
+		}
+
+	// dxy will have an implicit scaling factor of 4
+	Int16 *dxy = dbuf+2*src_size*src_size;
+	for(unsigned y=0; y<src_size; ++y)
+		for(unsigned x=0; x<src_size; ++x)
+			dxy[x+y*src_size] = dy[(x+1)%src_size + y*src_size] - dy[(x+src_size-1)%src_size + y*src_size];
+
+	for(unsigned y=0; y<src_size; ++y)
+	{
+		unsigned y2 = (y+1)%src_size;
+
+		for(unsigned x=0; x<src_size; ++x)
+		{
+			unsigned x2 = (x+1)%src_size;
+
+			unsigned i00 = x+y*src_size;
+			unsigned i10 = x2+y*src_size;
+			unsigned i01 = x+y2*src_size;
+			unsigned i11 = x2+y2*src_size;
+
+			// Cubic hermite at t=0.5: 0.5*p0 + 0.125*m0 + 0.5*p1 - 0.125*m1
+			unsigned i = x*2+y*2*size;
+			target[i] = src[i00];
+			target[i+1] = clamp(((src[i00]+src[i10])*8+dx[i00]-dx[i10])/16);
+			target[i+size] = clamp(((src[i00]+src[i01])*8+dy[i00]-dy[i01])/16);
+			// dyh0 and dyh1 will have an implicit scaling factor of 32
+			Int16 dyh0 = (dy[i00]+dy[i10])*8+dxy[i00]-dxy[i10];
+			Int16 dyh1 = (dy[i01]+dy[i11])*8+dxy[i01]-dxy[i11];
+			target[i+1+size] = clamp(((src[i00]+src[i10]+src[i01]+src[i11])*64+dyh0-dyh1)/256);
+		}
+	}
+}
+
+UInt8 FilmGrain::clamp(int v)
+{
+	return min(max(v, 0), 255);
+}
+
+void FilmGrain::set_coarseness(float c)
+{
+	shdata.uniform("coarseness", c/2.0f);
+}
+
+void FilmGrain::set_strength(float s)
+{
+	shdata.uniform("strength", s);
+}
+
+void FilmGrain::render(GL::Renderer &renderer, const GL::Texture2D &color, const GL::Texture2D &)
+{
+	current_layer = (current_layer+1)%layers;
+	shdata.uniform("grain_layer", static_cast<int>(current_layer));
+	texturing.attach(0, color);
+	renderer.set_texturing(&texturing);
+	renderer.set_shader_program(&shprog, &shdata);
+	mesh.draw(renderer);
+}
+
+
+FilmGrain::Template::Template():
+	size(256),
+	layers(16),
+	coarseness(2.0f),
+	strength(0.1f)
+{ }
+
+FilmGrain *FilmGrain::Template::create(unsigned, unsigned) const
+{
+	FilmGrain *grain = new FilmGrain(size, layers);
+	grain->set_coarseness(coarseness);
+	grain->set_strength(strength);
+	return grain;
+}
+
+
+FilmGrain::Template::Loader::Loader(Template &t):
+	DerivedObjectLoader<Template, PostProcessor::Template::Loader>(t)
+{
+	add("coarseness", &Template::coarseness);
+	add("layers", &Template::layers);
+	add("size", &Template::size);
+	add("strength", &Template::strength);
+}
+
+} // namespace DemoScene
+} // namespace Msp
diff --git a/source/filmgrain.h b/source/filmgrain.h
new file mode 100644
index 0000000..810b9a4
--- /dev/null
+++ b/source/filmgrain.h
@@ -0,0 +1,63 @@
+#ifndef MSP_DEMOSCENE_FILMGRAIN_H_
+#define MSP_DEMOSCENE_FILMGRAIN_H_
+
+#include <msp/gl/mesh.h>
+#include <msp/gl/postprocessor.h>
+#include <msp/gl/program.h>
+#include <msp/gl/programdata.h>
+#include <msp/gl/texture2darray.h>
+#include <msp/gl/texturing.h>
+
+namespace Msp {
+namespace DemoScene {
+
+class FilmGrain: public GL::PostProcessor
+{
+public:
+	struct Template: public PostProcessor::Template
+	{
+		class Loader: public DataFile::DerivedObjectLoader<Template, PostProcessor::Template::Loader>
+		{
+		public:
+			Loader(Template &t);
+		};
+
+		unsigned size;
+		unsigned layers;
+		float coarseness;
+		float strength;
+
+		Template();
+
+		virtual FilmGrain *create(unsigned, unsigned) const;
+	};
+
+private:
+	const Msp::GL::Mesh &mesh;
+	const Msp::GL::Program &shprog;
+	Msp::GL::ProgramData shdata;
+	Msp::GL::Texturing texturing;
+	unsigned size;
+	unsigned layers;
+	Msp::GL::Texture2DArray grain;
+	unsigned current_layer;
+
+public:
+	FilmGrain(unsigned = 256, unsigned = 16);
+
+private:
+	void generate_grain();
+	void bicubic2x(const UInt8 *, UInt8 *, Int16 *);
+	static UInt8 clamp(int);
+
+public:
+	void set_coarseness(float);
+	void set_strength(float);
+
+	virtual void render(GL::Renderer &, const GL::Texture2D &, const GL::Texture2D &);
+};
+
+} // namespace DemoScene
+} // namespace Msp
+
+#endif
diff --git a/source/launcher.cpp b/source/launcher.cpp
index 7dc9b98..aefa1be 100644
--- a/source/launcher.cpp
+++ b/source/launcher.cpp
@@ -7,6 +7,7 @@
 #include <msp/strings/regex.h>
 #include <msp/time/utils.h>
 #include "demo.h"
+#include "filmgrain.h"
 #include "launcher.h"
 #include "launchscreen.h"
 #include "vignette.h"
@@ -105,6 +106,7 @@ LauncherBase::LauncherBase(int argc, char **argv):
 	window.signal_close.connect(sigc::bind(sigc::mem_fun(this, &LauncherBase::exit), 0));
 	keyboard.signal_button_press.connect(sigc::bind_return(sigc::mem_fun(this, &LauncherBase::key_press), false));
 
+	GL::PipelineTemplate::register_postprocessor<FilmGrain>("film_grain");
 	GL::PipelineTemplate::register_postprocessor<Vignette>("vignette");
 }
 
-- 
2.43.0