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| Allegro 5 OpenGL depth test problem |
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DQBO1998
Member #16,394
June 2016
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I've been working on my first OpenGL project, I decided to implement it through Allegro 5.0.1 for the compiler MinGW 4.7.0. Currently I'm using TDM-GCC 4.7.1. The code I use to initialize OpenGL is. flags = ALLEGRO_WINDOWED | ALLEGRO_OPENGL_3_0 | ALLEGRO_OPENGL; //allegro flags Then to setup the projection matrix. 1 glMatrixMode(GL_PROJECTION);
2 glLoadIdentity();
3 L3D_perspective(FOV, (GLfloat)screen_width/(GLfloat)screen_height, 1.0f, 100.0f);
And the last one is for renderin, right now it's called every time after or before drawing. 1 glMatrixMode(GL_MODELVIEW);
2 glLoadIdentity();
I created a function for testing, it shows a textured quad on the given position and also can handle some rotation. 1void L3D_test_panel(GLfloat x, GLfloat y, GLfloat z, GLfloat x_angle, GLfloat y_angle, GLfloat z_angle, ALLEGRO_BITMAP *texture){
2
3 glPushMatrix();
4
5 glTranslatef(x, y, z);
6 glRotatef(x_angle, 1, 0, 0);
7 glRotatef(y_angle, 0, 1, 0);
8 glRotatef(z_angle, 0, 0, 1);
9 glBindTexture(GL_TEXTURE_2D, al_get_opengl_texture(texture));
10 glEnable(GL_TEXTURE_2D);
11
12 /* glClearDepth(1.0f);
13 glDepthFunc(GL_LESS);
14 glEnable(GL_DEPTH_TEST);*/
15
16 glBegin(GL_QUADS);
17
18 glTexCoord2f(0, 0); glVertex3f(-1, -1, -0);
19 glTexCoord2f(1, 0); glVertex3f(+1, -1, -0);
20 glTexCoord2f(1, 1); glVertex3f(+1, +1, -0);
21 glTexCoord2f(0, 1); glVertex3f(-1, +1, -0);
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23 glEnd();
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25 glPopMatrix();
26
27}
The problem is that when I try to apply depth testing the polygons still overlap. I could you tell me the right way to set it? |
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Elias
Member #358
May 2000
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The depth buffer has to be requested before creating a display. Simply put this before al_create_display: al_set_new_display_option(ALLEGRO_DEPTH_SIZE, 16, ALLEGRO_SUGGEST); -- |
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DQBO1998
Member #16,394
June 2016
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Thanks Elias, could you tell me when is it right to call glEnable(GL_DEPTH_TEST)? Because I want to know the "right" way. |
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Elias
Member #358
May 2000
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Just once in the beginning. Unless you need to draw some things without depth test, then you will have to call glEnable/glDisable every time you need it enabled/disabled for drawing. -- |
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