By: Aviel

Aviel — Fri, 03 Jun 2011 17:19:36 +0000

I have screwed around with it, and I only bug other people as a last resort. I probably screwed something up with the buffers, because I’ve verified that my shader isn’t the problem.

By: Peter Wallström

Peter Wallström — Fri, 03 Jun 2011 14:10:22 +0000

There is no common reason for that, if it’s done right it just works, if you did something wrong it should render something even though it’s probably wrong, the only things i can think of is if your running openGL 3.x in forward compatible mode and the shader doesn’t compile (and you have no error checking) it wouldn’t render anything.
or if you happen to render something over the screen it might also go black.
Alternatively since it uses a fbo for the shadow map if you don’t switch to the back buffer nothing will ever render.
So it’s probably something you did wrong for some reason, try messing around with the code and comment out parts and see what happens.

By: Aviel

Aviel — Fri, 03 Jun 2011 06:53:08 +0000

Is there any common reason why this code might just render blackness, or have I made a very specific and serious screwup?

By: Peter Wallström

Peter Wallström — Mon, 16 Aug 2010 18:02:02 +0000

Your right, it should be
pos= gl_ModelViewMatrix * gl_Vertex;

at certiain angles the difference is so small i didn’t notice it, the reason it’s there in the first place was because pos was originally used for something else.

By: ruxbin

ruxbin — Mon, 16 Aug 2010 14:48:56 +0000

Hey,nice shadow map tutorial.
But one thing I’m not quite sure is about the following code in vertex shader
“pos= gl_ModelViewProjectionMatrix * gl_Vertex;”
which I think should be pos=gl_ModelView * gl_Vertex. Because we are considering camera coordinates while multiplying with gl_ModelViewProjectionMatrix will transform to the clip coordinates space.
And after changing the code, I do see difference :)
Is that right? Or U write that code 4 some specific reason?
Thx

By: Peter Wallström

Peter Wallström — Tue, 04 May 2010 15:03:29 +0000

-old comments-

Comment by mziskandar on 2007:02:21 15:43
the tutorial im waiting for… great zeo!

Comment by mziskandar on 2007:02:21 19:26
sadly, im receiving: GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT_EXT error.

im using ati9600xt.

Comment by mziskandar on 2007:02:21 20:36
just want to share with anybody who failed to compile using vs2005.

remove:
#include

add:
#include
using namespace std;

Comment by eXile on 2007:08:30 10:51
Oh well …

… I just got it running in my Ati 9600 Pro (fixed some errors, like mziskandar said).

Comment by eXile on 2007:08:30 11:15
In glsl.frag REPLACE the three lines:
gl_TexCoord[2] = gl_TexCoord[2]/gl_TexCoord[2].w;

gl_TexCoord[2]=(gl_TexCoord[2]+ 1.0) * 0.5;

With:
vec4 texCoord2 = ((gl_TexCoord[2]/gl_TexCoord[2].w) + 1.0) * 0.5;

—

In glsl.frag REPLACE the line:
vec4 shadow = texture2D(texunit2,gl_TexCoord[2].xy);

With:
vec4 shadow = texture2D(texunit2,texCoord2.xy);

—

In glsl.frag REPLACE the line:
if((shadow.z+0.005) < gl_TexCoord[2].z)

With:
if((shadow.z+0.005) < texCoord2.z)

---

In glsl.frag REPLACE the three lines:

float fresnel =max((norm.z-0.6)*-1.0,0);

float diffuse = max(dot(lightVec, norm),0);

With:
float fresnel =max((norm.z-0.6)*-1.0,0.0);

float diffuse = max(dot(lightVec, norm),0.0);

---

In ZeoTut03a.cpp REPLACE the line:
glTexImage2D( GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT24, 2048, 2048, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_INT, NULL );

With:
glTexImage2D( GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, 2048, 2048, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_INT, NULL );

---

And recompile :-) If you are using Visual Studio 2005, you have to replace all "#include fstream.h" with "#include fstream" + an "using namespace

std;". If you never compiled an OpenGL-application before, you also need to download the glext.h from

http://oss.sgi.com/projects/ogl-sample/ABI/glext.h and place it into your Visual Studio 2005 installation path into …/VC/PlatformSDK/Include/gl.

Tested twice and working with above changes on a Ati 9600 Pro.

Comment by vinnythepoo on 2009:05:16 18:58
Thanks for your tutorials,
i have noticed that in your shadow mapping you declare the bias matrix, but you don’t use, and also you don’t invert anymore the camera, why ?

Comment by vinnythepoo on 2009:05:16 20:59
Forgot another thing, looks like that the instructions

glMatrixMode(GL_TEXTURE);
glLoadMatrixf(textureMatrix);

Completely corrupt the pipeline once the function ends, i see because i have an fps counter and it is not shown

Comment by Overlord on 2009:05:16 23:30
The bias matrix was previously used but i later put that in the shader, the downloadable code as an older version that i just didn’t update so the code on this page is the correct one, i will probably do a full update once i have time, i am working on like 6 different projects right now all with a close deadline, but once it’s done i think you will like it.

regarding glMatrixMode(GL_TEXTURE);, yea that might happen, just reset it with
glMatrixMode(GL_TEXTURE);
glLoadIdentity ();
I used the texture matrix because it’s convenient and easy to understand, in a production environment i would probably send a uniform to the shaders, it’s also something your required to do in 3.1.

Comment by vinnythepoo on 2009:05:17 07:41
I tried to reset the texture matrix but i get blank screen if i reset it, even after the end of the rendering function.
How can i solve this ? looks like the texture matrix is corrupted after being used

Comment by wallifin@hotmail.com on 2010:04:23 10:10
hi vinnythepoo,
try to change this lines
glMatrixMode(GL_PROJECTION);
glLoadMatrixf(cameraProjectionMatrix);

glMatrixMode(GL_TEXTURE);
glLoadMatrixf(textureMatrix);

glMatrixMode(GL_MODELVIEW);
glLoadMatrixf(cameraViewMatrix);
with:
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadMatrixf(cameraProjectionMatrix);

glMatrixMode(GL_TEXTURE);
glPushMatrix();
glLoadMatrixf(textureMatrix);

glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadMatrixf(cameraViewMatrix);

and at the end of rendering add this line:
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glPopMatrix();

glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glPopMatrix();

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glPopMatrix();
glFlush ();

for any questions send me a mail
reguards
walter :)
exsuse me for my bad english :(

Comments on: Depth Shadow maps

By: Aviel

By: Peter Wallström

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