Des polygones OpenGL collés en haut à gauche?

Question

J'utilise theallegro library et à travers OpenGL. Je permettent de tester la profondeur, puis sur Redimensionner que je fais:

glEnable(GL_CULL_FACE); 
    glCullFace(GL_BACK); 
    glEnable(GL_DEPTH_TEST); 
    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    glFrustum(0,event.display.width,event.display.height,0,1,300); 

Alors mon dessin ressemble à:

float BOX_SIZE = 200.0f; 
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 


     glRotatef(0.5, 0, 0.0f, 1.0f); 
     glBegin(GL_QUADS); 

     //Top face 
     glColor3f(1.0f, 1.0f, 0.0f); 
     glNormal3f(0.0, 1.0f, 0.0f); 
     glVertex3f(500 + -BOX_SIZE/2, BOX_SIZE/2, -BOX_SIZE/2); 
     glVertex3f(500 + -BOX_SIZE/2, BOX_SIZE/2, BOX_SIZE/2); 
     glVertex3f(500 + BOX_SIZE/2, BOX_SIZE/2, BOX_SIZE/2); 
     glVertex3f(500 + BOX_SIZE/2, BOX_SIZE/2, -BOX_SIZE/2); 

     //Bottom face 
     glColor3f(1.0f, 0.0f, 1.0f); 
     glNormal3f(0.0, -1.0f, 0.0f); 
     glVertex3f(-BOX_SIZE/2, -BOX_SIZE/2, -BOX_SIZE/2); 
     glVertex3f(BOX_SIZE/2, -BOX_SIZE/2, -BOX_SIZE/2); 
     glVertex3f(BOX_SIZE/2, -BOX_SIZE/2, BOX_SIZE/2); 
     glVertex3f(-BOX_SIZE/2, -BOX_SIZE/2, BOX_SIZE/2); 

     //Left face 
     glNormal3f(-1.0, 0.0f, 0.0f); 
     glColor3f(0.0f, 1.0f, 1.0f); 
     glVertex3f(-BOX_SIZE/2, -BOX_SIZE/2, -BOX_SIZE/2); 
     glVertex3f(-BOX_SIZE/2, -BOX_SIZE/2, BOX_SIZE/2); 
     glColor3f(0.0f, 0.0f, 1.0f); 
     glVertex3f(-BOX_SIZE/2, BOX_SIZE/2, BOX_SIZE/2); 
     glVertex3f(-BOX_SIZE/2, BOX_SIZE/2, -BOX_SIZE/2); 

     //Right face 
     glNormal3f(1.0, 0.0f, 0.0f); 
     glColor3f(1.0f, 0.0f, 0.0f); 
     glVertex3f(BOX_SIZE/2, -BOX_SIZE/2, -BOX_SIZE/2); 
     glVertex3f(BOX_SIZE/2, BOX_SIZE/2, -BOX_SIZE/2); 
     glColor3f(0.0f, 1.0f, 0.0f); 
     glVertex3f(BOX_SIZE/2, BOX_SIZE/2, BOX_SIZE/2); 
     glVertex3f(BOX_SIZE/2, -BOX_SIZE/2, BOX_SIZE/2); 

     glEnd(); 

     glEnable(GL_TEXTURE_2D); 

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 
     glColor3f(1.0f, 1.0f, 1.0f); 
     glBegin(GL_QUADS); 

     //Front face 
     glNormal3f(0.0, 0.0f, 1.0f); 
     glTexCoord2f(0.0f, 0.0f); 
     glVertex3f(-BOX_SIZE/2, -BOX_SIZE/2, BOX_SIZE/2); 
     glTexCoord2f(1.0f, 0.0f); 
     glVertex3f(BOX_SIZE/2, -BOX_SIZE/2, BOX_SIZE/2); 
     glTexCoord2f(1.0f, 1.0f); 
     glVertex3f(BOX_SIZE/2, BOX_SIZE/2, BOX_SIZE/2); 
     glTexCoord2f(0.0f, 1.0f); 
     glVertex3f(-BOX_SIZE/2, BOX_SIZE/2, BOX_SIZE/2); 

     //Back face 
     glNormal3f(0.0, 0.0f, -1.0f); 
     glTexCoord2f(0.0f, 0.0f); 
     glVertex3f(-BOX_SIZE/2, -BOX_SIZE/2, -BOX_SIZE/2); 
     glTexCoord2f(1.0f, 0.0f); 
     glVertex3f(-BOX_SIZE/2, BOX_SIZE/2, -BOX_SIZE/2); 
     glTexCoord2f(1.0f, 1.0f); 
     glVertex3f(BOX_SIZE/2, BOX_SIZE/2, -BOX_SIZE/2); 
     glTexCoord2f(0.0f, 1.0f); 
     glVertex3f(BOX_SIZE/2, -BOX_SIZE/2, -BOX_SIZE/2); 

     glEnd(); 
     glDisable(GL_TEXTURE_2D); 
//code goes here 
al_flip_display(); 

pour une raison quelconque le cube, peu importe la façon dont je traduis semble s'étendre de 0,0 et theres toujours un sommet à 0,0. Qu'est ce que j'ai mal fait? Merci

Answer 1

Je ne connais pas les détails de la bibliothèque allegro, mais deux choses me viennent à l'esprit lors de la lecture de votre extrait de code.

1. Pourquoi ne pas vous appelez glViewport(event.display.width,event.display.height) sur Redimensionner? L'appel glFrustum ne doit généralement pas dépendre de la taille d'affichage .

2. Avez-vous déjà appelé glMatrixMode(GL_MODELVIEW)? Dans le cas contraire, toutes les opérations de matrice seront appliquées à la matrice de projection .

J'espère que cela aide.