#include <stdafx.h>
#include<stdlib.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 20

//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;

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();
	glutDisplayFunc(DrawGLscene);
	glutIdleFunc(idle);
	glutReshapeFunc(Reshape);
	glutMainLoop();
}

void DrawGLscene(){
	
	glTranslatef(0.0f, -0.05f, 0.0f);
	Render_Particles();
	glFlush();
}

void Reshape(GLsizei w,GLsizei h){
	// resize viewport to new canvas size
	glViewport(0, 0, w, h);
	// change clipping region to have same w:h ratio as canvas
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();

	if (w <= h)
		gluOrtho2D(-1.0, 1.0, -1.0 * h/w, 1.0 * h/w);
	else
		gluOrtho2D(-1.0 * w/h, 1.0 * w/h, -1.0, 1.0);
}

void idle(){
	Activate_Particles();
	Adjust_Particles();
	glutPostRedisplay();
}

void Init_Particles(){
	int p;
	LoadBitmapTexture("./Particle.bmp", txParticle);
	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;

			Particles[p].R = R;
			Particles[p].G = G;
			Particles[p].B = B;
			R+=cR;
			G+=cG;
			B+=cB;
			if(R>1.0f){R=1.0f; cR=-cR;}
			if(R<0.0f){R=0.0f; cR=-cR;}
			if(G>1.0f){G=1.0f; cG=-cG;}
			if(G<0.0f){G=0.0f; cG=-cG;}
			if(B>1.0f){B=1.0f; cB=-cB;}
			if(B<0.0f){B=0.0f; cB=-cB;}
			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;
	// Enable textures and bind our particle texture
	glEnable(GL_TEXTURE_2D);
	glBindTexture(GL_TEXTURE_2D, txParticle);
	// Disable Depth testing.
	glDisable(GL_DEPTH_TEST);
	// Enable blending
	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_COLOR,GL_ONE);
	for(p=0; p<MAX_PARTICLES; p++){
		if(Particles[p].Active){
			glColor4f(Particles[p].R,
				Particles[p].G,
				Particles[p].B, 1.0f);
			glPushMatrix();
			glTranslatef(Particles[p].X,
				Particles[p].Y,
				Particles[p].Z);
			glBegin(GL_QUADS);
			glNormal3f(0.0f, 0.0f, 1.0f);
			glTexCoord2f(0.0f, 0.0f);
			glVertex3f(-Size, -Size, 0.0f);
			glTexCoord2f(1.0f, 0.0f);
			glVertex3f(Size, -Size, 0.0f);
			glTexCoord2f(1.0f, 1.0f);
			glVertex3f(Size, Size, 0.0f);
			glTexCoord2f(0.0f, 1.0f);
			glVertex3f(-Size, Size, 0.0f);
			glEnd();
			glPopMatrix();
		
		}
	}
}

bool LoadBitmapTexture(char * FileName, GLuint &texid){
	HBITMAP hBMP; // Handle Of The Bitmap
	BITMAP BMP; // Bitmap Structure
	glGenTextures(1, &texid); // Create The Texture
	hBMP=(HBITMAP)LoadImage(GetModuleHandle(NULL),
		FileName,
		IMAGE_BITMAP, 0, 0,
		LR_CREATEDIBSECTION | LR_LOADFROMFILE
		);
	if (!hBMP) // Does The Bitmap Exist?
		return FALSE; // If Not Return False
	GetObject(hBMP, sizeof(BMP), &BMP); // Get The Object
	// hBMP: Handle To Graphics Object
	// sizeof(BMP): Size Of Buffer For Object Information
	// &BMP: Buffer For Object Information
	glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
	// Pixel Storage Mode (Word Alignment / 4 Bytes)
	// Typical Texture Generation Using Data From The Bitmap
	glBindTexture(GL_TEXTURE_2D, texid);// Bind To The Texture ID
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
		GL_LINEAR); // Linear Min Filter
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
		GL_LINEAR); // Linear Mag Filter
	glTexImage2D(GL_TEXTURE_2D, 0, 3, BMP.bmWidth, BMP.bmHeight,
		0, GL_BGR_EXT, GL_UNSIGNED_BYTE, BMP.bmBits);
	DeleteObject(hBMP); // Delete The Object
	return TRUE; // Loading Was Successful
}