C GLUT drawing problems.
Post: #1
I've set up a rather fancy box with a direction pointer, and I've coded a 'laser'. The idea is the direction pointer extends 1000px in the direction specified by dir.
I've used NSBeep(); to check where my code stops, and I've concluded the code reaches the point at where It should draw the laser, but it does nothing onscreen.
Here's main.c:
I've used NSBeep(); to check where my code stops, and I've concluded the code reaches the point at where It should draw the laser, but it does nothing onscreen.
Here's main.c:
Code:
// Standard GLUT/C Setup.
#include <stdlib.h>
#include <GLUT/glut.h>
enum
{
false,
true
};
typedef unsigned char Bool;
typedef enum
{
ENTER = 3,
TAB = 9,
RETURN = 13,
ESC = 27,
SPACE = 32,
DEL = 127,
UP_ARROW, DOWN_ARROW, LEFT_ARROW, RIGHT_ARROW,
NUM_KEY_CODES
} KeyCode;
Bool key[NUM_KEY_CODES], keyDown[NUM_KEY_CODES], keyUp[NUM_KEY_CODES];
int lastFrameTime = 0;
float dt; // delta time (how much time in between frames, used for all movement calculations)
float shipPosX;
float shipPosY;
int dir;
void fire()
{
if (dir==0)
{
//works here
glBegin(GL_LINES);
glVertex3f(shipPosX,shipPosY,0.0f);
glVertex3f(shipPosX,shipPosY+500,0.0f);
glEnd();
}
else if (dir==90)
{
glBegin(GL_LINES);
glVertex3f(shipPosX,shipPosY,0.0f);
glVertex3f(shipPosX+500,shipPosY,0.0f);
glEnd();
}
else if (dir==180)
{
glBegin(GL_LINES);
glVertex3f(shipPosX,shipPosY,0.0f);
glVertex3f(shipPosX,shipPosY-500,0.0f);
glEnd();
}
else if (dir==-180)
{
glBegin(GL_LINES);
glVertex3f(shipPosX,shipPosY,0.0f);
glVertex3f(shipPosX-500,shipPosY,0.0f);
glEnd();
}
}
void resetKeyboardInput(void)
{
int i;
for (i = 0; i < NUM_KEY_CODES; i++)
{
keyDown[i] = false;
keyUp[i] = false;
}
}
void keyboard(unsigned char rawKeyCode, int x, int y)
{
if (rawKeyCode < NUM_KEY_CODES)
{
key[rawKeyCode] = true;
keyDown[rawKeyCode] = true;
}
}
void keyboardUp(unsigned char rawKeyCode, int x, int y)
{
if (rawKeyCode < NUM_KEY_CODES)
{
key[rawKeyCode] = false;
keyUp[rawKeyCode] = false;
}
}
void keyboardSpecial(int rawKeyCode, int x, int y)
{
switch (rawKeyCode)
{
case GLUT_KEY_LEFT:
key[LEFT_ARROW] = true;
keyDown[LEFT_ARROW] = true;
break;
case GLUT_KEY_UP:
key[UP_ARROW] = true;
keyDown[UP_ARROW] = true;
break;
case GLUT_KEY_RIGHT:
key[RIGHT_ARROW] = true;
keyDown[RIGHT_ARROW] = true;
break;
case GLUT_KEY_DOWN:
key[DOWN_ARROW] = true;
keyDown[DOWN_ARROW] = true;
break;
}
}
void keyboardSpecialUp(int rawKeyCode, int x, int y)
{
switch (rawKeyCode)
{
case GLUT_KEY_LEFT:
key[LEFT_ARROW] = false;
keyUp[LEFT_ARROW] = true;
break;
case GLUT_KEY_UP:
key[UP_ARROW] = false;
keyUp[UP_ARROW] = true;
break;
case GLUT_KEY_RIGHT:
key[RIGHT_ARROW] = false;
keyUp[RIGHT_ARROW] = true;
break;
case GLUT_KEY_DOWN:
key[DOWN_ARROW] = false;
keyUp[DOWN_ARROW] = true;
break;
}
}
void display(void)
{
if (lastFrameTime == 0)
{
lastFrameTime = glutGet(GLUT_ELAPSED_TIME);
}
int now = glutGet(GLUT_ELAPSED_TIME);
int elapsedMilliseconds = now - lastFrameTime;
float dt = elapsedMilliseconds / 1000.0f;
lastFrameTime = now;
// "key" is cached locally so that it stays down until the next key up event
if (key[LEFT_ARROW])
{
shipPosX -= 200.0f * dt;
dir = -90;
}
if (key[RIGHT_ARROW])
{
shipPosX += 200.0f * dt;
dir = 90;
}
if (key[UP_ARROW])
{
shipPosY += 200.0f * dt;
dir = 0;
}
if (key[DOWN_ARROW])
{
shipPosY -= 200.0f * dt;
dir =180;
}
if (key[SPACE])
{
fire();
}
// also do wasd to demonstrate discrete "keyDown" events
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// This code is where you put all drawing code. v
// draw the ship @ the position
glBegin(GL_LINE_LOOP);
glVertex3f(shipPosX-40,shipPosY-40, 0.0f);
glVertex3f(shipPosX+40,shipPosY-40, 0.0f);
glVertex3f(shipPosX+40, shipPosY+40, 0.0f);
glVertex3f(shipPosX-40,shipPosY+40,0.0f);
glEnd();
glBegin(GL_LINE_LOOP);
glVertex3f(shipPosX-30,shipPosY-30, 0.0f);
glVertex3f(shipPosX+30,shipPosY-30, 0.0f);
glVertex3f(shipPosX+30, shipPosY+30, 0.0f);
glVertex3f(shipPosX-30,shipPosY+30,0.0f);
glEnd();
if (dir==0)
{
glBegin(GL_LINES);
glVertex3f(shipPosX,shipPosY,0.0f);
glVertex3f(shipPosX,shipPosY+40,0.0f);
glEnd();
}
else if (dir==90)
{
glBegin(GL_LINES);
glVertex3f(shipPosX,shipPosY,0.0f);
glVertex3f(shipPosX+40,shipPosY,0.0f);
glEnd();
}
else if (dir==180)
{
glBegin(GL_LINES);
glVertex3f(shipPosX,shipPosY,0.0f);
glVertex3f(shipPosX,shipPosY-40,0.0f);
glEnd();
}
else if (dir==-90)
{
glBegin(GL_LINES);
glVertex3f(shipPosX,shipPosY,0.0f);
glVertex3f(shipPosX-40,shipPosY,0.0f);
glEnd();
}
// That's the ship drawn
// drawframe
glutSwapBuffers();
// do this to clear the key ups and key downs for each frame
resetKeyboardInput();
}
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();
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
//glutInitWindowSize(1680,1050);
glutInitWindowSize(640, 480);
glutCreateWindow("GLUT Program");
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutIdleFunc(idle);
glutFullScreen();
glutKeyboardFunc(keyboard);
glutKeyboardUpFunc(keyboardUp);
glutSpecialFunc(keyboardSpecial);
glutSpecialUpFunc(keyboardSpecialUp);
//glutFullScreen();
glutMainLoop();
return EXIT_SUCCESS;
}~ Bring a Pen ~
Post: #2
You're calling fire to draw before the color buffer gets cleared, so you're drawing your laser beam and then erasing everything! Move your clear to the top of display(), like:
Code:
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
