I started writing a small particle fountain in OpenGL using glut. I've got the particles to show up and bounce around the screen, like I intended to. so When I first run the program I get this
And in about 2 secs that changes to this
I tried messing with the code to see what's causing this issue and I haven't been able to solve it.
This is what I have in the program so far
- Int main()
- Init_particles() //initializes everything, called once in the main
- void Activate_Particles(); //activates the particle
- void Adjust_particle() //sets the speed and bouncing of the particle
void Render_particle() //renders the particle, this function is called in the DrawGLScene() function.
void idle()// idle function that calls Adjust_particles and Activate_particles, followed by the glutPostRedisplay()
Here is the full code:
// particle_fountain.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include<stdlib.h> #include <stdio.h> #include<Windows.h> #include <time.h> #include <GL\glut.h> #include<GL\GLU.h> #define MAX_PARTICLES 100 #define MAX_BOUNCE_COUNT 10 #define MAX_PARTICLE_AGE 50 //Colours float R = 0.8f; float G = 0.2f; float B = 0.0f; float cR = 0.001f; float cG = 0.002f; float cB = 0.003f; float Size = 0.01f; //size for points GLuint txParticle; GLuint txPlane; struct PARTICLE { float X,Y,Z; // Current position float sX,sY,sZ; // Current Speed/Movement float tX,tY,tZ; // Target Speed/Movement float R,B,G; // Particle Colour bool Active; // Is particle Active int Age; // Age of the particle int MaxAge; // Maximum Age before particle dies int BounceCount; } Particles[MAX_PARTICLES]; void Init_Particles(); void Activate_Particles(); void Adjust_Particles(); void Render_Particles(); bool LoadBitmapTexture(char * FileName, GLuint &texid); void idle(); void DrawGLscene(); void Reshape(GLsizei w, GLsizei h); int main(int argc, char** argv){ glutInit(&argc,argv); glutCreateWindow("Particle fountain"); Init_Particles(); glTranslatef(0.0f, -0.7f, 0.0f); glutDisplayFunc(Render_Particles); glutIdleFunc(idle); glutMainLoop(); } void idle(){ Activate_Particles(); Adjust_Particles(); glutPostRedisplay(); } void Init_Particles(){ int p; srand((int)time(NULL)); for(p=0; p<MAX_PARTICLES; p++){ Particles[p].Active = FALSE; Particles[p].tX = 0.0f; Particles[p].tY = -0.1f; Particles[p].tZ = 0.0f; } } void Activate_Particles(){ int p; for(p=0; p<MAX_PARTICLES; p++){ if(!Particles[p].Active){ // Start the particle at 0,0,0 origin Particles[p].X = 0.0f; Particles[p].Y = 0.0f; Particles[p].Z = 0.0f; // The following lines set a random speed value Particles[p].sX = (((float)((rand() % 100) + 1)) / 1000.0f) - 0.05f; Particles[p].sY = (((float)((rand() % 100) + 50)) / 500.0f); Particles[p].sZ = (((float)((rand() % 100) + 1)) / 1000.0f) - 0.05f; // We also activate the particle Particles[p].Active = true; // Set it's Age to zero Particles[p].Age = 0; // We also assign a max age to the particles Particles[p].MaxAge = MAX_PARTICLE_AGE; // We Also reset the bouncecount to zero Particles[p].BounceCount = 0; return; } } } void Adjust_Particles(){ int p; for(p=0; p<MAX_PARTICLES; p++){ // We move the speed towards the target speed by 1/20 (5%) Particles[p].sX+= (Particles[p].tX - Particles[p].sX) / 20.0f; Particles[p].sY+= (Particles[p].tY - Particles[p].sY) / 20.0f; Particles[p].sZ+= (Particles[p].tZ - Particles[p].sZ) / 20.0f; // Then we adjust the position of // the particle by the new speed Particles[p].X+= Particles[p].sX; Particles[p].Y+= Particles[p].sY; Particles[p].Z+= Particles[p].sZ; // Now for the bounce code. if(Particles[p].Y < 0.0f){ Particles[p].Y = 0.0f; Particles[p].sY = -Particles[p].sY; Particles[p].BounceCount++; if(Particles[p].BounceCount > MAX_BOUNCE_COUNT){ Particles[p].Active = FALSE; } } // And finally the age check Particles[p].Age++; if(Particles[p].Age > Particles[p].MaxAge){ Particles[p].Active = FALSE; } } } void Render_Particles(){ int p; glBegin(GL_POINTS); for(p=0; p<MAX_PARTICLES; p++){ if(Particles[p].Active){ glColor4f(1.0f, 1.0f, 1.0f, 0.5f); glVertex3f(Particles[p].X, Particles[p].Y, Particles[p].Z); } } glEnd(); glFlush(); } 
