From d864699c5ddd744ee7376c0d752b6bbb771429a2 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Fri, 8 Nov 2019 23:02:47 +0100
Subject: Update lattice multiple times per frame

Controlled by `--lupf` _Lattice updates per frame_

MLUPS are now calculated and displayed.

While performance is still bad compared to a optimized GPU implementation (such
as [1] or [2]) this improves the situation.

[1]: https://tree.kummerlaender.eu/projects/symlbm_playground/
[2]: https://code.kummerlaender.eu/boltzgen/about/
---
 src/glfw/window.cc           |  1 -
 src/main.cc                  | 34 ++++++++++++++++++++--------------
 src/shader/code/collide.glsl | 14 +++++++-------
 src/shader/code/extra.glsl   |  2 +-
 src/shader/code/vertex.glsl  |  2 +-
 5 files changed, 29 insertions(+), 24 deletions(-)

diff --git a/src/glfw/window.cc b/src/glfw/window.cc
index 77be947..c0074ad 100644
--- a/src/glfw/window.cc
+++ b/src/glfw/window.cc
@@ -14,7 +14,6 @@ Window::Window(const std::string& title):
 	_handle(glfwCreateWindow(_width, _height, title.c_str(), NULL, NULL)) {
 	if ( _handle != nullptr ) {
 		glfwMakeContextCurrent(_handle);
-		glfwSwapInterval(0);
 		if ( glewInit() == GLEW_OK ) {
 			_good = true;
 		}
diff --git a/src/main.cc b/src/main.cc
index 8e9fa9a..7d2ebe8 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -24,7 +24,7 @@
 
 #include "timer.h"
 
-GLuint maxLUPS = 100;
+GLuint maxLUPF = 100;
 GLuint nX = 512;
 GLuint nY = 256;
 
@@ -184,25 +184,19 @@ int render() {
 			MVP = getMVP(world_width, world_height);
 		}
 
-		if ( update_lattice && timer::millisecondsSince(last_lattice_update) >= 1000/maxLUPS ) {
+		if ( update_lattice ) {
 			if ( timer::secondsSince(last_lups_update) >= 1.0 ) {
-				std::cout << "\rComputing about " << statLUPS << " lattice updates per second." << std::flush;
+				std::cout << "\r~ " << nX*nY * statLUPS / timer::secondsSince(last_lups_update) * 1e-6 << " MLUPS" << std::flush;
 				statLUPS = 0;
 				last_lups_update = timer::now();
 			}
 
-			statLUPS += 1;
-
 			if ( tick ) {
 				interact_shader->workOn(tick_buffers);
-				collide_shader->workOn(tick_buffers);
 				extra_shader->workOn(tick_buffers);
-				tick = false;
 			} else {
 				interact_shader->workOn(tock_buffers);
-				collide_shader->workOn(tock_buffers);
 				extra_shader->workOn(tock_buffers);
-				tick = true;
 			}
 
 			/// Perform collide & stream steps
@@ -213,7 +207,19 @@ int render() {
 				collide_shader->setUniform("iT", iT);
 				iT += 1;
 
-				collide_shader->dispatch(nX, nY);
+				for (auto i=0; i < maxLUPF; ++i) {
+					if ( tick ) {
+						collide_shader->workOn(tick_buffers);
+						tick = false;
+					} else {
+						collide_shader->workOn(tock_buffers);
+						tick = true;
+					}
+
+					collide_shader->dispatch(nX, nY);
+				}
+
+				statLUPS += maxLUPF;
 			}
 
 			if ( display_mode == DisplayMode::CURL ) {
@@ -289,18 +295,18 @@ bool parseArguments(int argc, char* argv[]) {
 	for ( int i = 1; i < argc; ++i ) {
 		const auto& arg = std::string_view(argv[i]);
 
-		if ( arg == "--lups" ) {
+		if ( arg == "--lupf" ) {
 			if ( i+1 < argc ) {
 				try {
 					i       += 1;
-					maxLUPS = std::stoi(argv[i]);
+					maxLUPF = std::stoi(argv[i]);
 				}
 				catch ( std::invalid_argument& ex ) {
-					std::cerr << "Maximum lattice updates per second malformed." << std::endl;
+					std::cerr << "Maximum lattice updates per frame malformed." << std::endl;
 					return false;
 				}
 			} else {
-				std::cerr << "Maximum lattice updates per second undefined." << std::endl;
+				std::cerr << "Maximum lattice updates per frame undefined." << std::endl;
 				return false;
 			}
 		}
diff --git a/src/shader/code/collide.glsl b/src/shader/code/collide.glsl
index 0f9b2bd..ef1ba93 100644
--- a/src/shader/code/collide.glsl
+++ b/src/shader/code/collide.glsl
@@ -1,7 +1,7 @@
 static const std::string COLLIDE_SHADER_CODE = R"(
 #version 430
 
-layout (local_size_x = 1, local_size_y = 1) in;
+layout (local_size_x = 32, local_size_y = 1) in;
 
 layout (std430, binding=1) buffer bufferCollide  { float collideCells[];  };
 layout (std430, binding=2) buffer bufferStream   { float streamCells[];   };
@@ -32,7 +32,7 @@ const float latticeCharVelocity = 0.005;
 
 /// Unit conversion
 
-const float resolution    = max(nX,nY);
+const float resolution    = min(nX,nY);
 const float convLength    = physCharLength / resolution;
 const float convTime      = latticeCharVelocity / physCharVelocity * physCharLength / resolution;
 const float convVelocity  = convLength / convTime;
@@ -110,7 +110,7 @@ int getMaterial(uint x, uint y) {
 
 float density(uint x, uint y) {
 	const uint idx = indexOfLatticeCell(x, y);
-	float d = 0.;
+	float d = 0.f;
 	for ( int i = 0; i < q; ++i ) {
 		d += collideCells[idx + i];
 	}
@@ -118,7 +118,7 @@ float density(uint x, uint y) {
 }
 
 vec2 velocity(uint x, uint y, float d) {
-	return 1./d * vec2(
+	return 1.f/d * vec2(
 		get(x,y, 1, 0) - get(x,y,-1, 0) + get(x,y, 1, 1) - get(x,y,-1,-1) + get(x,y, 1,-1) - get(x,y,-1,1),
 		get(x,y, 0, 1) - get(x,y, 0,-1) + get(x,y, 1, 1) - get(x,y,-1,-1) - get(x,y, 1,-1) + get(x,y,-1,1)
 	);
@@ -127,7 +127,7 @@ vec2 velocity(uint x, uint y, float d) {
 /// Equilibrium distribution
 
 float equilibrium(float d, vec2 v, int i, int j) {
-	return w(i,j) * d * (1 + 3*comp(i,j,v) + 4.5*sq(comp(i,j,v)) - 1.5*sq(norm(v)));
+	return w(i,j) * d * (1.f + 3.f*comp(i,j,v) + 4.5f*sq(comp(i,j,v)) - 1.5f*sq(norm(v)));
 }
 
 /// Material number meaning (geometry is only changed by the interaction shader)
@@ -179,10 +179,10 @@ void main() {
 
 	if ( isBulkFluidCell(material) ) {
 		if ( isInflowCell(material) ) {
-			v = vec2(min(float(iT)/5000.0*latticeCharVelocity, latticeCharVelocity), 0.0);
+			v = vec2(min(float(iT)/100.f*latticeCharVelocity, latticeCharVelocity), 0.f);
 		}
 		if ( isOutflowCell(material) ) {
-			d = 1.0;
+			d = 1.f;
 		}
 
 		if ( show_quality ) {
diff --git a/src/shader/code/extra.glsl b/src/shader/code/extra.glsl
index b8483ae..4b149fb 100644
--- a/src/shader/code/extra.glsl
+++ b/src/shader/code/extra.glsl
@@ -9,7 +9,7 @@ layout (std430, binding=4) buffer bufferExtra { float extraCells[]; };
 uniform uint nX;
 uniform uint nY;
 
-const float convLength = 1.0 / float(max(nX,nY));
+const float convLength = 1.0 / float(min(nX,nY));
 
 /// Array indexing
 
diff --git a/src/shader/code/vertex.glsl b/src/shader/code/vertex.glsl
index 6ad54cf..10abf0c 100644
--- a/src/shader/code/vertex.glsl
+++ b/src/shader/code/vertex.glsl
@@ -58,7 +58,7 @@ float restrictedCurl(float curl) {
 	if ( abs(curl) < 1.0 ) {
 		return 0.5;
 	} else {
-		return 0.5 + 0.5*min(1.0, curl / (50*palette_factor));
+		return 0.5 + 0.5*min(1.0, curl / sq(palette_factor));
 	}
 }
 
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