From 7fbe0814d52ba861a02b0560d4e6872845ef241e Mon Sep 17 00:00:00 2001
From: ccolin
Date: Tue, 22 Dec 2020 13:15:23 +0100
Subject: initial commit

---
 src/boid.cc | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 src/boid.cc

(limited to 'src/boid.cc')

diff --git a/src/boid.cc b/src/boid.cc
new file mode 100644
index 0000000..9eeea41
--- /dev/null
+++ b/src/boid.cc
@@ -0,0 +1,108 @@
+#include "main_window.hh"
+
+#include <QVector3D>
+#include <QRandomGenerator>
+
+
+struct Fish {
+	QVector3D pos;
+	QVector3D vel;
+	float size;
+	float dist = 10;
+	float sqdist;
+
+	OpenGLMesh mesh;
+
+	Fish(QVector3D pos, OpenGLMesh mesh)
+		:pos(pos),
+		 sqdist(dist * dist),
+		 mesh(mesh) {}
+
+	void step() {
+		pos += vel;
+		mesh.mat.setToIdentity();
+		QMatrix4x4 rot;
+		rot.lookAt(pos, vel, {0, 1, 0});
+		mesh.mat.translate(pos);
+		// mesh.mat = rot * mesh.mat;
+	}
+
+	bool in_neighborhood(const QVector3D &p) const {
+		return (p - pos).lengthSquared() < sqdist;
+	}
+};
+
+
+struct Banc {
+	QVector<Fish> fishes;
+
+	Banc() {}
+
+	Banc(size_t nfishes) {
+		OpenGLMesh fish_mesh = OpenGLMesh({
+				0, .1, 0,
+				-.0866, -.05, 0,
+				.0866, -.05, 0,
+			});
+		QRandomGenerator *rng = QRandomGenerator::global();
+		for (size_t i = 0; i < nfishes; i++) {
+			Fish fish({
+					(float) (rng->generateDouble() * 3 - 1.5),
+					(float) (rng->generateDouble() * 3 - 1.5),
+					(float) (rng->generateDouble() * 3 - 1.5)
+				}, fish_mesh);
+			fishes.append(fish);
+		}
+	}
+
+	void step() {
+		QVector<Fish> neighbors;
+		for (Fish &fish : fishes) {
+			QVector3D neighbors_cog;
+			QVector3D neighbors_vel;
+			size_t nneighbors = 0;
+			for (Fish &fish_b : fishes) {
+				if (fish_b.in_neighborhood(fish.pos)) {
+					nneighbors++;
+					neighbors_cog += fish_b.pos;
+					neighbors_vel += fish_b.vel;
+				}
+			}
+			neighbors_cog /= nneighbors;
+			neighbors_vel /= nneighbors;
+			QVector3D v1 = -(fish.pos - neighbors_cog);
+			QVector3D v2 = fish.vel - neighbors_vel;
+			QVector3D v3 = neighbors_cog - fish.pos;
+			QVector3D v = 1.5 * v1 + v2 + v3;
+			float L = .001;
+			fish.vel = (1-L) * fish.vel + L * v;
+			fish.step();
+		}
+	}
+};
+
+
+Banc banc;
+
+void MainWindow::init() {
+	banc = Banc(10);
+	for (Fish &fish : banc.fishes) {
+		glw.meshes.append(&fish.mesh);
+	}
+}
+
+
+void MainWindow::step() {
+	banc.step();
+	OpenGLWidget::instance->update();
+}
+
+
+void OpenGLWidget::paintGL() {
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+	for (const Fish &fish : banc.fishes) {
+		glUniformMatrix4fv(model_attr, 1, GL_FALSE, fish.mesh.mat.data());
+		glBindVertexArray(fish.mesh.vao);
+		glDrawArrays(GL_TRIANGLES, 0, fish.mesh.nverts);
+	}
+}
-- 
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