From 315a8c2dff9b76ac5e1ebbef265f13ac19d65e3d Mon Sep 17 00:00:00 2001
From: Stijn Buys <ingar@osirion.org>
Date: Sun, 16 Nov 2008 13:53:44 +0000
Subject: engine trails

---
 src/render/particles.cc | 144 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)
 create mode 100644 src/render/particles.cc

(limited to 'src/render/particles.cc')

diff --git a/src/render/particles.cc b/src/render/particles.cc
new file mode 100644
index 0000000..94a3a07
--- /dev/null
+++ b/src/render/particles.cc
@@ -0,0 +1,144 @@
+/*
+   render/particles.cc
+   This file is part of the Osirion project and is distributed under
+   the terms of the GNU General Public License version 2
+*/
+
+#include "render/particles.h"
+#include "render/camera.h"
+#include "render/gl.h"
+#include "render/draw.h"
+#include "render/textures.h"
+
+#include "core/application.h"
+namespace render {
+
+/* ---- class Particle --------------------------------------------- */
+
+Particle::Particle(const math::Vector3f &location, float time) : particle_location(location)
+{
+	particle_time = time;
+}
+
+Particle::Particle(const math::Vector3f &location, const math::Vector3f &up, const math::Vector3f &left, float time) : particle_location(location), particle_up(up), particle_left(left)
+{
+	particle_time = time;
+}
+
+/* ---- class ParticleStream --------------------------------------- */
+
+ParticleStream::ParticleStream(const math::Vector3f &location, const math::Color &color, float radius, size_t texture, core::EntityControlable *entity, bool oriented) : particles_location(location), particles_color(color)
+{
+	particles_texture = texture;
+	particles_entity = entity;
+	if (!entity) {
+		particles_oriented = false;
+	} else {
+		particles_oriented = oriented;
+	}
+
+	particles_radius = radius;
+	
+	particles_timeout = 1.5f; // a particles lives for 3 seconds
+	particles_eject = 0.02f; // a particle is ejected every 0.2 seconds
+
+	particles_last_eject = 0; // timestamp of the last eject
+}
+
+ParticleStream::~ParticleStream()
+{
+	for (Particles::iterator it = particles_stream.begin(); it != particles_stream.end(); it++) {
+		delete (*it);
+	}
+	particles_stream.clear();
+}
+
+void ParticleStream::draw() {
+	float now = core::application()->time();
+
+	// remove dead particles
+	Particles::iterator it = particles_stream.begin();
+	while ((it  != particles_stream.end()) && ((*it)->time() + particles_timeout <= now)) {
+		delete (*it);
+		particles_stream.erase(it);
+		it = particles_stream.begin();
+	}
+
+	// add new particles
+	if (particles_last_eject + particles_eject <= now) {
+		if (particles_entity) {
+			float u = 0;
+			if ((particles_entity->eventstate() == core::Entity::ImpulseInitiate ) || (particles_entity->eventstate() == core::Entity::Impulse)) {
+				u = 1.0f;
+			} else if(particles_entity->eventstate() == core::Entity::Normal) {
+				u = particles_entity->thrust();
+			}
+			if (u > 0.0f) {
+				math::Vector3f l(particles_entity->location() + (particles_entity->axis() * location()));
+				Particle *p = 0;
+				if (particles_oriented) {
+					p = new Particle(l, particles_entity->axis().up(), particles_entity->axis().left(), now);
+				} else {
+					p = new Particle(l, now);
+				}
+				particles_stream.push_back(p);
+			}
+		} else {
+			particles_stream.push_back(new Particle(location(), now));
+		}
+		particles_last_eject = now;
+	}
+
+	math::Vector3f quad[4];
+
+	if (particles_stream.size()) {
+		Textures::bind(particles_texture);
+		gl::begin(gl::Quads);
+
+		for (Particles::reverse_iterator rit = particles_stream.rbegin(); rit != particles_stream.rend(); rit++) {
+			Particle *particle = (*rit);
+	
+			if (particles_oriented) {
+				quad[0].assign(particle->up() - particle->left());
+				quad[1].assign(particle->up() + particle->left());
+				quad[2].assign(particle->up() * -1 + particle->left());
+				quad[3].assign(particle->up() * -1 - particle->left());
+			} else {
+				quad[0].assign(Camera::axis().up() - Camera::axis().left());
+				quad[1].assign(Camera::axis().up() + Camera::axis().left());
+				quad[2].assign(Camera::axis().up() * -1 + Camera::axis().left());
+				quad[3].assign(Camera::axis().up() * -1 - Camera::axis().left());
+			}
+	
+			float t = now - particle->time();
+			float f = 0;
+
+			if (t < particles_timeout * 0.1f) {
+				f = t / (0.1f * particles_timeout);
+			} else {
+				t = t - particles_timeout * 0.1f;
+				f = t / (0.9f * particles_timeout);
+				f = 1.0 - f;
+			}
+
+			f *= f;
+			float radius = particles_radius * f;
+			particles_color.a = f;
+			gl::color(particles_color);
+	
+			glTexCoord2f(0,1);
+			gl::vertex(particle->location() + quad[0] * radius);
+			glTexCoord2f(0,0);
+			gl::vertex(particle->location() + quad[1] * radius);
+			glTexCoord2f(1,0);
+			gl::vertex(particle->location() + quad[2] * radius);
+			glTexCoord2f(1,1);
+			gl::vertex(particle->location() + quad[3] * radius);
+			Stats::quads++;
+		}
+
+		gl::end();
+	}
+}
+
+} // namespace render
-- 
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