glBlendFunc - 'Blue Screen of Death'

OpenGL OpenGL: Basic Coding
1

Hi,

Just looking for advice … on some graphics cards, the code below seems to cause a complete system crash :frowning:

The loaded textures do not contain an alpha channel (24bit). I wanted to blend two textures and found that this code achieved what I wanted … in this case it renders a light spotlight texture on a floor plane and then I blend a floor texture …

Is this code likely to be the culprite or should I be looking elsewhere ?

Thanks

Andrew

glNewList(fGenList, GL_COMPILE);
glColor3ub(180, 180, 180);
glBindTexture(GL_TEXTURE_2D, TexNames[cSpotLight]);
glBegin(GL_QUADS);
glNormal3f(0.0, 1.0, 0.0);
glTexCoord2f(0.0, 0.0); glVertex3f(-100.0, -17.0, -100.0);
glTexCoord2f(0.0, 1.0); glVertex3f(-100.0, -17.0, 100.0);
glTexCoord2f(1.0, 1.0); glVertex3f( 100.0, -17.0, 100.0);
glTexCoord2f(1.0, 0.0); glVertex3f( 100.0, -17.0, -100.0);
glEnd;

glEnable(GL_BLEND);
glBlendFunc(GL_DST_COLOR, GL_ONE_MINUS_DST_COLOR);
glDepthFunc(GL_EQUAL);

glBindTexture(GL_TEXTURE_2D, TexNames[cCarpet]);
  glBegin(GL_QUADS);
  glNormal3f( 0.0, 1.0, 0.0);
	  glTexCoord2f( 0.0,  0.0); glVertex3f(-100.0,  -17.0, -100.0);
	  glTexCoord2f( 0.0, 20.0); glVertex3f(-100.0,  -17.0,  100.0);
	  glTexCoord2f(20.0, 20.0); glVertex3f( 100.0,  -17.0,  100.0);
	  glTexCoord2f(20.0,  0.0); glVertex3f( 100.0,  -17.0, -100.0);
  glEnd;

glDepthFunc(GL_LESS);
glDisable(GL_BLEND);

glEndList;

2

I believe some video cards don’t support destination colors, this might be why

3

What graphics card and driver you are having?
You can always blame the driver for this happening.

4

Originally posted by AndrewJJ:
glEnd;
…
glEnd;
…
glEndList;
These lines do nothing. You must use the brackets for function calls, otherwise the compiler evaluates this to, well, nothing.

glEnd(); is correct, as is glEndList();

[This message has been edited by zeckensack (edited 06-04-2002).]

5

I’ve no idea as yet as to which particular cards are causing this problem … I don’t really want to be forced to use RGBA textures but maybe I’ll have too … unless there’s another way of emulating a projected spotlight …

(I’m one of those Delphi programmers … we don’t need the empty closing brackets !)

Thanks for the feedback

Andrew