main.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <GL/freeglut.h>
#include <GL/gl.h>
#include <GL/glu.h>

#define ROW 100
#define COLUMN 100
#define FIREINTENSITY_SIZE 36

unsigned char textureData[ROW][COLUMN][3];
unsigned int table[ROW][COLUMN];

int fireIntensity[FIREINTENSITY_SIZE] = {
    0x070707, 0x1f0707, 0x2f0f07,
    0x470f07, 0x571707, 0x671f07,
    0x771f07, 0x8f2707, 0x9f2f07,
    0xaf3f07, 0xbf4707, 0xc74707,
    0xDF4F07, 0xDF5707, 0xDF5707,
    0xD75F07, 0xD7670F, 0xcf6f0f,
    0xcf770f, 0xcf7f0f, 0xCF8717,
    0xC78717, 0xC78F17, 0xC7971F,
    0xBF9F1F, 0xBF9F1F, 0xBFA727,
    0xBFA727, 0xBFAF2F, 0xB7AF2F,
    0xB7B72F, 0xB7B737, 0xCFCF6F,
    0xDFDF9F, 0xEFEFC7, 0xFFFFFF
};

void setColor(int i, int j, int fI){
    int R = (fI & 0xff0000) >> 16;
    int G = (fI & 0x00ff00) >> 8;
    int B = (fI & 0x0000ff);

    textureData[i][j][0] = R;
    textureData[i][j][1] = G;
    textureData[i][j][2] = B;
}

void fireLoop(){
    int i, j;
    for (i = ROW-1; i > 0; i--) {
        for (j = 0; j < COLUMN; j++) {
            if (i != 0){
                int fireIntensity = (table[i-1][j] - (int)rand()%3);
                if(fireIntensity >= 0)
                    table[i][j] = fireIntensity;
                else
                    table[i][j] = 0;
            }
        }
    }
}

void renderScene(){

    glClear(GL_COLOR_BUFFER_BIT);
    int i,j;
    fireLoop();

    for (i = 0; i < ROW; i++) {
        for (j = 0; j < COLUMN; j++) {
            setColor(i, j, fireIntensity[(int)table[i][j]]);
        }
    }
    // Update Texture
    glTexSubImage2D(GL_TEXTURE_2D, 0 ,0, 0, COLUMN, ROW, GL_RGB, GL_UNSIGNED_BYTE, (void*)textureData);

    glBegin(GL_QUADS);
        glTexCoord2f(0.0, 0.0); glVertex2f(-1.0, -1.0);
        glTexCoord2f(1.0, 0.0); glVertex2f( 1.0, -1.0);
        glTexCoord2f(1.0, 1.0); glVertex2f( 1.0,  1.0);
        glTexCoord2f(0.0, 1.0); glVertex2f(-1.0,  1.0);
    glEnd();

    glutSwapBuffers();
}

void framebuffer_size_callback(int w, int h){

    if(h == 0)
        h = 1;

    glViewport(0, 0, w, h);

}

void setup(){
    glClearColor(0.1, 0.1, 0.2, 1.0);

    srand(time(NULL));

    int i,j;

    // Clear table
    for (i = 0; i < ROW; i++) {
        for (j = 0; j < COLUMN; j++) {
            table[i][j] = FIREINTENSITY_SIZE-1;
        }
    }

    // Clean texture
    for (i = 0; i < ROW; i++) {
        for (j = 0; j < COLUMN; j++) {
            textureData[i][j][0] = textureData[i][j][1] = textureData[i][j][2] = 0;
        }
    }

    // Create texture
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, COLUMN, ROW, GL_FALSE, GL_RGB, GL_UNSIGNED_BYTE, (void*)textureData);

    // Config texture
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

    // Enable texture
    glEnable(GL_TEXTURE_2D);

}

void timerFunction(int val){
    glutPostRedisplay();

    glutTimerFunc(33, timerFunction, 1);
}

int main(int argc, char **argv){
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowSize(600, 600);
    glutCreateWindow("Doom Fire");
    glutDisplayFunc(renderScene);
    glutReshapeFunc(framebuffer_size_callback);
    glutTimerFunc(10, timerFunction, 1);

    setup();

    glutMainLoop();


    return 0;
}