OpenGL Platformer

#include <stdlib.h>
#include <stdio.h>
#include <GLUT/glut.h>

float deltaTime = 0.0f;
float playerX = 20.0f;
float playerY = 20.0f;
float enemyX = 500.0f;
float enemyY = 10.0f;
float prevtime = 0.0f;
int lastFrameTime = 0;
void makeQuad(float,float,float,float);
//int wkey, akey, skey, dkey = 0;
int keyDown[256];
int playerspeed = 500;
float gravity = 0.0f;
/*
Compile using:
gcc -framework GLUT -framework OpenGL main.c -o game
Then run using:
./game

Controls:
WASD

Goal:
Evade the small cube. If you hit the cube, your X will be reset to 20. Take that player!
*/

void keyPressed(unsigned char key, int x, int y) {
    keyDown[key]=1;
}

void keyUp(unsigned char key, int x, int y){
    keyDown[key]=0;
}

void display(void){

    if(!lastFrameTime){
        lastFrameTime = glutGet(GLUT_ELAPSED_TIME);
    }
    int now = glutGet(GLUT_ELAPSED_TIME);
    int elapsedMilliseconds = now - lastFrameTime;
    float deltaTime = elapsedMilliseconds / 1000.0f;
    lastFrameTime = now;

    //printf("\ndeltaTime is: %d", deltaTime);
    int windowWidth = glutGet(GLUT_WINDOW_WIDTH);
    //playerX+=1000.0F*deltaTime;



    //--------------PLAYER CONTROLS---------


    if(keyDown[100]){
        playerX+=playerspeed*deltaTime;
    }
    if(keyDown[97]){
        playerX-=playerspeed*deltaTime;
    }
    if(keyDown[119]&&playerY<21){
        playerY+=100;
    }

    if(playerX>windowWidth){
        playerX-=windowWidth;
        //printf("true");
    }
    if(playerX<0){
        playerX+=windowWidth;
    }
    if(playerY>19){
        gravity-=1*deltaTime;
        playerY+=gravity;
    }
    else{
        gravity=0;
    }
    if(playerX<enemyX+10&&playerX>enemyX-10&&playerY<enemyY+10&&playerY>enemyY-10){
        playerX = 20;
    }


    //---------------ENEMY CONTROLS---------------
    enemyX-=100*deltaTime;
    if(enemyX<0){
        enemyX+=windowWidth;
    }




    //--------------DRAW THINGS-------------------
    //printf("\nwindowWidth is: %d", windowWidth);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix();
    glTranslatef(playerX, playerY,0.0f);
    makeQuad(0,0,20,40);
    glPopMatrix();
    glPushMatrix();
    glTranslatef(enemyX, enemyY,0.0f);
    makeQuad(0,0,20,20);
    glPopMatrix();
    glutSwapBuffers();
}



void reshape(int width, int height){
    glViewport(0,0,width,height);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0, width, 0, height);
    glMatrixMode(GL_MODELVIEW);
}

void idle(void){
    glutPostRedisplay();
}

void makeQuad(float x, float y, float width, float height){
    glBegin(GL_QUADS);
    glVertex2f(x-(width/2), y-(height/2));
    glVertex2f(x+(width/2), y-(height/2));
    glVertex2f(x+(width/2), y+(height/2));
    glVertex2f(x-(width/2), y+(height/2));
    glEnd();
}

int main(int argc, char** argv){
    glutInit(&argc, argv);


    //glutKeyboardFunc(keyPressed);

    glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
    glutInitWindowSize(800, 600);

    glutCreateWindow("Wolfos' epic game");

    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutIdleFunc(idle);

    glutKeyboardFunc(keyPressed);
    glutKeyboardUpFunc(keyUp);

    glutMainLoop();
    return 0;
}