Setup for GLSL – Example

void setShaders() {

	char *vs,*fs;

	v = glCreateShader(GL_VERTEX_SHADER);
	f = glCreateShader(GL_FRAGMENT_SHADER);	

	vs = textFileRead("toon.vert");
	fs = textFileRead("toon.frag");

	const char * vv = vs;
	const char * ff = fs;

	glShaderSource(v, 1, &vv,NULL);
	glShaderSource(f, 1, &ff,NULL);

	free(vs);free(fs);

	glCompileShader(v);
	glCompileShader(f);

	p = glCreateProgram();

	glAttachShader(p,v);
	glAttachShader(p,f);

	glLinkProgram(p);
	glUseProgram(p);
}

void setShaders() {

	char *vs,*fs;

	v = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB);
	f = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);	

	vs = textFileRead("toon.vert");
	fs = textFileRead("toon.frag");

	const char * vv = vs;
	const char * ff = fs;

	glShaderSourceARB(v, 1, &vv,NULL);
	glShaderSourceARB(f, 1, &ff,NULL);

	free(vs);free(fs);

	glCompileShaderARB(v);
	glCompileShaderARB(f);

	p = glCreateProgramObjectARB();

	glAttachObjectARB(p,v);
	glAttachObjectARB(p,f);

	glLinkProgramARB(p);

	glUseProgramObjectARB(p);
}

9 comments on “Setup for GLSL – Example”

1. nautilus on 23/01/2013 at 1:50 AM said:

   No meh, There are no memory leaks in it because he free all the resources before getting out the routine.

   Reply ↓
2. meh on 14/10/2012 at 2:27 PM said:

   This code contains memory leaks. *vs and *fs both point to data on the heap never deleted.

   Reply ↓
3. Dileep S on 12/07/2012 at 5:21 PM said:

   I am a beginner in GLSL. I could not find the code corresponding toon.vert and toon.frag where I can see contents of these files ? Regards, Dileep S

   Reply ↓
4. Matt on 02/07/2012 at 7:40 PM said:

   Where have you got textFileRead() function from? My Code::Blocks says that “error: ´textFileRead´ was not declared in this scope”. I tried to include fstream, but without success.

   Reply ↓
   • ARF on 10/07/2012 at 12:12 AM said:

     I wrote it

     Don’t know how to help you in this as I0ve never worked with Code::Blocks. Could it be a project settings issue?

     Antonio

     Reply ↓
5. Charisma on 24/02/2012 at 3:09 PM said:

   Hi I got an error of compiling your program. It says that it cannot link _glAttachShader , _glCreateShader and so on.

   Error 3 error LNK2001: unresolved external symbol __imp____glewAttachShader C:UserscharismaDocumentsOpenGLGLSL Tutorialglutglsl_2.0ogl.obj glutglsl

   Reply ↓
   • György Straub on 03/03/2012 at 4:40 PM said:

     From the amount of information you’ve provided it seems that you’ve got trouble with GLEW. Check that it’s compiled, linked, the linker libraries are where your project expects them to be, and also make sure that libglew is linked against before opengl32, i.e.

     -lglew
     -lopengl32

     Cheers,
     György

     Reply ↓
6. Sam on 20/06/2011 at 11:55 PM said:

   Currently, I am running the example code..
   I intentionally commented out
   glEnable(GL_DEPTH_TEST);
   to check what the difference is.
   I found that the rendering difference is pretty big.
   I mean they look quite different.

   Would you explain what the effect of using / not using glEnable(GL_DEPTH_TEST); ?

   Another question is…
   I accidentally set gluPerspective(45, ratio, 0, 1000);
   but nothing was displayed… I spent quite some time in figuring it out,
   and I found that I shouldn’t use 0 as the ‘near’ value.
   Is this a general rule I have to follow ?

   Thanks a lot.

   Reply ↓
   • ARF on 21/06/2011 at 12:04 AM said:

     Hi Sam,

     Depth testing allows the objects to be properly displayed according to their distance, or depth, to the camera. Without it objects are rendered by the order they appear in the source code, and possibly incorrectly overlapping each other.

     As for gluPerspective, yes, zero is definitely not a recommended value. The near value must be greater than zero.

     Reply ↓