Problema de mezcla OpenGL

Question

Quiero dibujar el acuario (contenedor) de pie sobre la mesa. Las paredes del acuario deben mezclarse.

Pero, si dibujo mesa primero y luego acuario consigo:
- mirando desde arriba de la mesa: ok
- mirando desde la parte inferior de la tabla: mal, sigo viendo acuario

Si dibujo primero Aquariun y luego mesa, obtengo:
- mirando desde arriba de la mesa: mal, las paredes del acuario no tienen ningún efecto sobre la mesa (afectan el fondo)
- mirando desde la parte inferior de la tabla : mal, aún veo acuario

Hay imagen que lo explica:

http://img213.imageshack.us/img213/6609/pictureem.jpg

Código: main.cpp

int DrawGLScene(GLvoid) 
{ 
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
glLoadIdentity(); 
glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA); 

Cam.SetPrespective(); 

//---------------- 
GLfloat LightPosition0[]= { 0.0, 0.0, 0.2, 1.0f }; 
GLfloat LightAmbient0[]= { 0, 0, 0, 1.0f }; 
GLfloat LightDiffuse0[]= { 1.0f, 1.0f, 1.0f, 1.0f }; 
GLfloat LightSpecular0[]= { 1.0f, 1.0f, 1.0f, 1.0f }; 
glLightfv(GL_LIGHT0, GL_AMBIENT, LightAmbient0); // Setup The Ambient Light 
glLightfv(GL_LIGHT0, GL_POSITION,LightPosition0); // Position The Light 
glLightfv(GL_LIGHT0, GL_DIFFUSE, LightDiffuse0); // Setup The Diffuse Light 
glLightfv(GL_LIGHT0, GL_SPECULAR, LightSpecular0); // Setup The Diffuse Light 
glEnable(GL_LIGHT0); 
glEnable(GL_COLOR_MATERIAL); 
glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE); 

//---------------- 

glLightfv(GL_LIGHT1, GL_AMBIENT, LightAmbient); // Setup The Ambient Light 
glLightfv(GL_LIGHT2, GL_POSITION,LightPosition); // Position The Light 
glLightfv(GL_LIGHT2, GL_DIFFUSE, LightDiffuse); // Setup The Diffuse Light 


drawContainer(); //container drawn first in this example 
//.. draw other things 
drawTable(); 
drawGround(); 

/* 
    //.. draw other things 
    drawTable(); 
    drawGround(); 
    drawContainer(); //container drawn last in this example 
*/ 
    CheckKeys(); 
if(mouse) 
{ 
CheckMouse(); 
} 

return TRUE; 
} 

void drawTable() 
{ 
glColor3f(1.0f, 0.5f, 1.0f); 

GLfloat cx = MIN_X+(MAX_X-MIN_X)/2.0f; 
GLfloat cy = MIN_Y-0.1f; 
GLfloat cz = MIN_Z+(MAX_Z-MIN_Z)/2.0f; 
GLfloat cr = sqrt((MAX_X-MIN_X)*(MAX_X-MIN_X)+(MAX_Z-MIN_Z)*(MAX_Z-MIN_Z))*0.85f; 
int th = 5.0f; //centerPieceThickness 

drawCylinder(cx,cy,cz,th,cr); 
glColor3f(0.7f, 0.5f, 0.5f); 
drawCylinder(MAX_X+cr*0.155f, cy-th, MAX_Z+cr*0.155f, 25*th, cr*0.035f); 
drawCylinder(MAX_X+cr*0.155f, cy-th, MIN_Z-cr*0.155f, 25*th, cr*0.035f); 
drawCylinder(MIN_X-cr*0.155f, cy-th, MIN_Z-cr*0.155f, 25*th, cr*0.035f); 
drawCylinder(MIN_X-cr*0.155f, cy-th, MAX_Z+cr*0.155f, 25*th, cr*0.035f); 
} 

void drawGround() 
{ 
int th = 5.0f; 
GLfloat cx = MIN_X+(MAX_X-MIN_X)/2.0f; 
GLfloat cy = MIN_Y-0.1f; 
GLfloat cz = MIN_Z+(MAX_Z-MIN_Z)/2.0f; 
GLfloat cr = sqrt((MAX_X-MIN_X)*(MAX_X-MIN_X)+(MAX_Z-MIN_Z)*(MAX_Z-MIN_Z))*8.5f; 
glColor3f(0.0f, 0.6f, 0.0f); 
drawCylinder(cx,cy-26*th,cz,10.f,cr); 
} 

void drawContainer() 
{ 
    glColor3f(0.2f, 0.2f, 0.2f); 
drawCuboid(MIN_X-0.5, MAX_X+0.5f, MIN_Y-0.5, MIN_Y+0.5, MIN_Z-0.5f, MIN_Z+0.5f); 
drawCuboid(MIN_X-0.5, MAX_X+0.5f, MIN_Y-0.5, MIN_Y+0.5, MAX_Z-0.5f, MAX_Z+0.5f); 
drawCuboid(MIN_X-0.5, MAX_X+0.5f, MAX_Y-0.5, MAX_Y+0.5, MIN_Z-0.5f, MIN_Z+0.5f); 
drawCuboid(MIN_X-0.5, MAX_X+0.5f, MAX_Y-0.5, MAX_Y+0.5, MAX_Z-0.5f, MAX_Z+0.5f); 
drawCuboid(MIN_X-0.5, MIN_X+0.5f, MIN_Y-0.5, MAX_Y+0.5, MIN_Z-0.5f, MIN_Z+0.5f); 
drawCuboid(MIN_X-0.5, MIN_X+0.5f, MIN_Y-0.5, MAX_Y+0.5, MAX_Z-0.5f, MAX_Z+0.5f); 
drawCuboid(MAX_X-0.5, MAX_X+0.5f, MIN_Y-0.5, MAX_Y+0.5, MIN_Z-0.5f, MIN_Z+0.5f); 
drawCuboid(MAX_X-0.5, MAX_X+0.5f, MIN_Y-0.5, MAX_Y+0.5, MAX_Z-0.5f, MAX_Z+0.5f); 
drawCuboid(MIN_X-0.5, MIN_X+0.5f, MIN_Y-0.5, MIN_Y+0.5, MIN_Z-0.5f, MAX_Z+0.5f); 
drawCuboid(MIN_X-0.5, MIN_X+0.5f, MAX_Y-0.5, MAX_Y+0.5, MIN_Z-0.5f, MAX_Z+0.5f); 
drawCuboid(MAX_X-0.5, MAX_X+0.5f, MIN_Y-0.5, MIN_Y+0.5, MIN_Z-0.5f, MAX_Z+0.5f); 
drawCuboid(MAX_X-0.5, MAX_X+0.5f, MAX_Y-0.5, MAX_Y+0.5, MIN_Z-0.5f, MAX_Z+0.5f); 

glEnable(GL_BLEND); 
glDisable(GL_DEPTH_TEST); 
glColor4f(0.5f,1.0f,1.0f,0.12f); 

drawCuboid(MIN_X,MAX_X,MIN_Y,MAX_Y,MIN_Z,MAX_Z); 

glDisable(GL_BLEND); 
glEnable(GL_DEPTH_TEST); 


} 

Answer 1

Sospecho que el problema es causado por el glDisable (GL_DEPTH_TEST) en drawContainer(). Sugiero comentar las líneas GL_DEPTH_TEST: ¿el acuario parece correcto con respecto a la mesa y el piso en ese caso?

Answer 2

Para opacas (polys no transparentes): Habilita GL_DEPTH_TEST y renderiza todo esto.

Para polys transparentes: Mantenga GL_DEPTH_TEST pero desactive la escritura de profundidad con glDepthMask(GL_FALSE) y luego ordene los polígonos transparentes de atrás hacia adelante antes de renderizar.

Consulte también FAQ