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glutBitmapCharacter help

Started by Quasius Apr 25, 2005 at 10:19 PM 9 replies 14.6k views

Original Post

Apr 25, 2005 at 10:19 PM

Can someone explain to me or tell me where to find exactly what glutBitmapCharacter is doing? The official documentation was not sufficient, as I am still quite confused. First, how do I set the color? It seems to have a mind of its own. Sometime it appears black (useless on a black background) and other times it shows up as other colors. Nether glColor3f nor glClearColor seem to affect it. And when I have the coordinates it's drawn at follow my camera, the text pops in and out of existance depending on how I rotate the camera. All I want is for some text to print and remain in a static position as I move around. This seems like it would be easy, but the (seemingly) erratic behavior of this function is driving me nuts. Thanks for any info. [Edited by - Quasius on April 25, 2005 11:39:10 PM]

Quasius

Apr 25, 2005 at 10:57 PM

Nevermind. I founf the answere here: http://www.lighthouse3d.com/opengl/glut/index.php?bmpfontortho

edit: actually, that just answers 1 of my question. I would still like to know how to set the color it outputs in. Thanks.

[Edited by - Quasius on April 25, 2005 11:57:42 PM]

nprz

Apr 26, 2005 at 12:38 AM

glColor3f, or glColor3ub, or any of those should change the color of the text. That is how I change the color.

Brother Bob

Apr 26, 2005 at 1:48 AM

nprz is correct that glColor will change the raster color aswell, but you also have to know how glColor interacts with the raster color to not get confused. The raster color is separate from the primary color, and it set at the time glRasterPos is called. When glRasterPos is called, the primary color is copied to the raster color, so changing the primary color AFTER glRasterPos will not change the raster color; you must change the primary color before.

Quasius

Apr 26, 2005 at 10:38 PM

Then why is this not giving me a red text? The color seems to change depend on where I am looking (which might effect the last color rendered).

void RenderBitmapString(float x, float y, void *font, char *string){    char *c;  glColor3f(1.0, 0.0, 0.0);//print timer in red  glRasterPos2f(x, y);  for (c=string; *c != '\0'; c++)    glutBitmapCharacter(font, *c);}void DisplayTimer(){	int seconds_left;	time_left -= 0.1;	char time_string[5];	seconds_left = ceil(time_left);	itoa(seconds_left, time_string, 10);	RenderBitmapString(5,30,GLUT_BITMAP_TIMES_ROMAN_24, time_string);	if (time_left < 0)//restart level if times up		first_frame = true;}

[Edited by - Quasius on April 27, 2005 12:38:43 AM]

nprz

Apr 27, 2005 at 12:05 AM

so try calling glColor before glRasterPos :)

Quasius

Apr 27, 2005 at 12:21 AM

Quote:
Original post by nprz
so try calling glColor before glRasterPos :)

Oops. I did actually, and it didn't work. Then just to check, I tried calling it after to see if it worked (it didn't), but I accidently pasted the wrong version. Corrected in above post.

Brother Bob

Apr 27, 2005 at 1:40 AM

Do you have anything enabled that affects the color of a fragment? Like fogging, lighting, texturing, or anything else?

Quasius

Apr 27, 2005 at 2:14 AM

Quote:
Original post by Brother Bob
Do you have anything enabled that affects the color of a fragment? Like fogging, lighting, texturing, or anything else?

Lighting is enabled. How will that affect it?

Brother Bob

Apr 27, 2005 at 3:00 AM

When lighting is enabled, the primary color is calculated from the lighting equation instead of being taken from glColor and equivalent functions. So instead of setting the raster color with glColor, the last used normal is used in the lighting equation to calculate a new primary color, and that color is used during rasterization.

Quasius

Apr 27, 2005 at 3:09 AM

Thanks. I just disabled the lighting right before the function call than immediatly renabled it. Now the timer is red. Thanks for the help.

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