From d2f792c6fee2a6e78dcf2fff77f43ef036c58877 Mon Sep 17 00:00:00 2001
From: jjesswan <jessica_wan@brown.edu>
Date: Fri, 10 May 2024 01:49:32 -0400
Subject: saving parts

---
 src/particlesystem.cpp | 176 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 176 insertions(+)
 create mode 100644 src/particlesystem.cpp

(limited to 'src/particlesystem.cpp')

diff --git a/src/particlesystem.cpp b/src/particlesystem.cpp
new file mode 100644
index 0000000..104b449
--- /dev/null
+++ b/src/particlesystem.cpp
@@ -0,0 +1,176 @@
+#include "particlesystem.h"
+#include <iostream>
+
+particlesystem::particlesystem()
+{
+
+}
+
+std::pair<double,double> sample_complex_gaussian(){
+    double uniform_1 = (double)rand() / (RAND_MAX);
+    double uniform_2 = (double)rand() / (RAND_MAX);
+
+    // set a lower bound on zero to avoid undefined log(0)
+    if (uniform_1 == 0)
+    {
+        uniform_1 = 1e-10;
+    }
+    if (uniform_2 == 0)
+    {
+        uniform_2 = 1e-10;
+    }
+
+    // real and imaginary parts of the complex number
+    double real = sqrt(-2*log(uniform_1)) * cos(2*M_PI*uniform_2);
+    double imag = sqrt(-2*log(uniform_1)) * sin(2*M_PI*uniform_2);
+
+    return std::make_pair(real, imag);
+}
+
+float getRandomInRange(float max, float min){
+    return min + static_cast <float> (rand()) /( static_cast <float> (RAND_MAX/(max-min)));
+
+}
+
+Eigen::Vector3f particlesystem::getRandomInitialVel(){
+
+
+    std::pair<float, float> r = sample_complex_gaussian();
+    return factor*Eigen::Vector3f(r.first, getRandomInRange(1.f, 10.f), r.second);
+}
+
+void particlesystem::init(std::vector<Eigen::Vector3f> verts){
+    // make sure to set m_verts
+    setVerts(verts);
+
+    m_particles.reserve(4000);
+
+    for (Eigen::Vector3f v : m_verts){
+        Particle p;
+        p.pos = Eigen::Vector3f(v);
+        p.vel = getRandomInitialVel();
+
+
+        m_particles.push_back(p);
+    }
+
+
+    glGenVertexArrays(1, &VAO);
+    glGenBuffers(1, &VBO);
+    glBindVertexArray(VAO);
+
+    glBindBuffer(GL_ARRAY_BUFFER, VBO);
+    glBufferData(GL_ARRAY_BUFFER, m_vertices.size()*sizeof(float), m_vertices.data(), GL_STATIC_DRAW);
+
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2*sizeof(float), (void*)0);
+
+    // unbind
+    glEnableVertexAttribArray(0);
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+}
+
+
+void particlesystem::update(double deltaTime){
+
+    // add new particles
+    for (int i=0; i<m_particles.size(); i++){
+        int particle_index = getUnusedParticleIndex();
+        if (particle_index == -1) continue;
+        if (particle_index >= m_particles.size() - 1 || particle_index >= m_verts.size() - 1) continue;
+        respawn_particle(m_particles[particle_index], m_verts[particle_index]);
+
+    }
+
+
+    float dt = deltaTime;
+    // update all particles values
+    for (Particle &p : m_particles){
+       p.life -= deltaTime * getRandomInRange(.01f, .5f);
+
+        // if particle is still alive, update pos
+        if (p.life >= 0.f){
+            p.vel += gravity*dt;
+            p.pos += p.vel * dt * 10.f;
+
+        }
+
+    }
+}
+
+
+
+// finds the first instance of a particle that is dead, and returns its index so it can be replaced
+int particlesystem::getUnusedParticleIndex(){
+
+    // search from last used index
+    for (int i=lastUsedIndex; i<m_verts.size(); ++i){
+        if (m_particles[i].life <= 0.f){
+            lastUsedIndex = i;
+            return i;
+        }
+    }
+
+    // otherwise do linear search up to last used
+    for (int i=0; i<lastUsedIndex; ++i){
+        if (m_particles[i].life <= 0.f){
+            lastUsedIndex = i;
+            return i;
+        }
+    }
+
+    // if no dead ones found, don't respawn
+    lastUsedIndex = 0;
+    //std::cout << "first particle override!" << std::endl;
+    return -1;
+}
+
+void particlesystem::respawn_particle(Particle &p, Eigen::Vector3f new_pos){
+
+    p.pos = new_pos;
+    p.vel = getRandomInitialVel(); // TODO: change to more accurate vel
+
+    // reset life
+    p.life = 1.f;
+
+}
+
+void particlesystem::draw(Shader *shader, Camera  m_camera){
+
+    shader->bind();
+
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE);
+
+
+    // activate texture
+//    glActiveTexture(GL_TEXTURE10);
+//    glBindTexture(GL_TEXTURE_CUBE_MAP, skybox_tex);
+//    glUniform1i(glGetUniformLocation(shader->id(), "cubeMap"), 9); // bind texture at slot 9
+
+
+    // manually set view and projection, for non-translating view
+    Eigen::Matrix4f projection = m_camera.getProjection();
+    Eigen::Matrix4f view = m_camera.getView();
+   // view.col(3) = Eigen::Vector4f(0, 0, 0, 0);
+
+    glUniformMatrix4fv(glGetUniformLocation(shader->id(), "view"), 1, GL_FALSE, view.data());
+    glUniformMatrix4fv(glGetUniformLocation(shader->id(), "projection"), 1, GL_FALSE, projection.data());
+   // shader->setUniform("model", model);
+
+    int i = 0;
+    for (Particle p : m_particles){
+        if (p.life >= 0.f){
+            shader->setUniform("offset", p.pos);
+            shader->setUniform("alpha", p.life);
+
+            glBindVertexArray(VAO);
+            glDrawArrays(GL_TRIANGLES, 0, m_vertices.size());
+            glBindVertexArray(0);
+            i++;
+        }
+    }
+    shader->unbind();
+
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+
+}
-- 
cgit v1.2.3-70-g09d2