Problem: Allegro 5 & Opengl text drawing

Ghost101

I have a problem with the allegro 5 and opengl combination

I want to use al_draw_textf for my fps counter. But it is always behind the perspective of opengl.

I use the functions in given sequence.
Can somebody please help me???

Code:

#SelectExpand
  1void Renderer::InitOpenGL()
  2    {
  3        glMatrixMode( GL_PROJECTION );
  4        glLoadIdentity();
  5        gluPerspective(45.0f,(GLfloat)WIDTH/(GLfloat)HEIGHT,0.1f,100.0f);
  6
  7        glMatrixMode(GL_MODELVIEW);
  8
  9        glEnable(GL_TEXTURE_2D);
 10        glEnable(GL_CULL_FACE);
 11        glEnable(GL_DEPTH_TEST);
 12        glShadeModel(GL_SMOOTH);
 13
 14        glDepthMask(GL_TRUE);
 15
 16        //glPolygonMode(GL_FRONT,GL_LINE);
 17        glPolygonMode(GL_FRONT,GL_FILL);
 18
 19        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 20    }

#SelectExpand
  1void Renderer::RenderBlock(float x, float y, float z, ALLEGRO_BITMAP* texture)
  {
      glPushMatrix();
      glTranslatef(x,y,z);
      glBindTexture(GL_TEXTURE_2D, al_get_opengl_texture(texture));
  6
      glBegin(GL_QUADS);
          // Front Face
          //glNormal3f( 0.0f, 0.0f, 1.0f);
          glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);
          glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);
          glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);
          glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);
          // Back Face
          //glNormal3f( 0.0f, 0.0f,-1.0f);
          glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
          glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);
          glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);
          glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
 20
          // All the other faces :D
      glEnd();
      glPopMatrix();
  }

#SelectExpand
  void Renderer::DrawFPS(ALLEGRO_FONT *font, int fps)
  {
      al_draw_textf(font, al_map_rgb(255, 255, 255), 5, 5, 0, "FPS: %i", fps);
  }

Elias

Easiest way will be a brute foce method like:

// Just pseudocode, look up documentationf or all functions.

// right after al_create_display
glGetDoublev(GL_MODELVIEW_MATRIX, modelview)
glGetDoublev(GL_PROJECTION_MATRIX, projection)
glGetDoublev(GL_VIEWPORT, viewport)

// then later, before using Allegro functions
glViewport(viewport[0], viewport[1], viewport[2], viewport[3])
glMatrixMode(GL_PROJECTION)
gLoadMatrixd(projection)
glMatrixMode(GL_MODELVIEW)
gLoadMatrixd(modelview)

Basically, store whatever is the current transformation setup Allegro uses, then restore to that whenever using Allegro functions.

Alternatively you could check Allegro's source code and just set up the same matrices.

Ghost101

ok thanks for the reaction but is there no way to not brute force it I wass thinking something like making one viewport transparant

or else is there a way to use text in opengl

Elias

If you want the text to not be affected by the perspective transform, you need to disable that transform, no matter how you draw it.

SiegeLord

Why not just push and pop the relevant matrices?

Ghost101

ok that is something I am going to try

Thread #610149. Printed from Allegro.cc