Serious problem about Blending wth Texture

OpenGL Development JOGL Development
#1

hi all,

i’ve written a little chunk of code in jogl, which takes me hours to figure out what’s the problem is;

here is the situation which makes me thinks this a bug of jogl…

i first read in some texture(not mapped to anything yet), and left GL_TEXTURE_2D enabled;

then i tried to draw some simple points, with GL_BLEND enabled and glBlendFunc(GL_SRC_ALPHA,GL_ONE);

i use {R,G,B,Alpha} color format, but the points just won’t show up; after i disabled GL_TEXTURE_2D after readin the texture, the points thing works fine;

BUT, it’s really strange, since in standard OpenGL blending along with texture mapping should be supported…

dunno i got some idea wrong here, so anyone who can give more explanations?

thx in adv.

#2

I’ve got the answer… from the_phantom@GameDev.net

As you left the state enabled when OGL came to draw the points it saw that it needed to use a texture and thus looked at the active texture coords, it saw it only had one texture unit active and thus looked at the location it stored teh current texture coords, as these texture coords default to (0,0,0,1) (iirc) that is where it tried to sample before applying it to the final points output colour.