shader using texture2D on an fbo

advanced
#1

probably relating to this post
http://forum.openframeworks.cc/t/fbo-addon-for-0.06/1866/0

here is a simple do nothing shader (thanks memo)

  
  
------ fragment  
uniform sampler2D tex0;  
void main()  
{  
	gl_FragColor = texture2D(tex0, gl_TexCoord[0].st);  
}  
  
------- vert  
void main() {  
    gl_TexCoord[0] = gl_MultiTexCoord0;  
    gl_Position    = ftransform();  
}

In my app I do:

  
  
------- setup  
myfbo.allocate(1024, 768, true);  
testShader.loadShader("data/basic");  
  
------- draw  
  
// draw something into the fbo  
myfbo.swapIn();  
myfbo.setupScreenForMe();  
ofCircle(50,50,20);  
myfbo.swapOut();  
myfbo.setupScreenForThem();  
  
// bind shader then draw fbo  
ofSetColor(255,255,255);  
testShader.setShaderActive(true);  
myfbo.draw(0,0,1024,768);  
testShader.setShaderActive(false);

It draws nothing. Ive already tested the fbo drawing without shader, works fine.

In the fbo addon, if I comment out GLEE_ARB_texture_rectangle so that it uses:

  
  
//allocate  
texData.tex_w = ofNextPow2(w);  
texData.tex_h = ofNextPow2(h);  
texData.tex_t = 1.0f;  
texData.tex_u = 1.0f;

The fbo is now showing when I draw it with the shader, but it is coming out slightly fuzzy.

texData.tex_w = ofNextPow2(w);
texData.tex_h = ofNextPow2(h);

is coming out as

texData.tex_w = 1024;
texData.tex_h = 1024;

Any thoughts as to whats going on?

Many thanks

#2

Hi Chris,

if you are using GL_TEXTURE_RECT-textures you’ll have to use samplerRECT/textureRECT to access the pixels of your texture.

something along this lines should work

  
  
Code:  
------ fragment  
#extension GL_ARB_texture_rectangle : enable   
  
uniform samplerRECT tex0;  
void main()  
{  
   gl_FragColor = textureRECT(tex0, gl_TexCoord[0].st);  
}  
  
------- vert  
void main() {  
    gl_TexCoord[0] = gl_MultiTexCoord0;  
    gl_Position    = ftransform();  
}

this is from the top of my head, and untested code, so your mileage may vary :wink:

accessing 1D- or 3D-textures is analogous, use sampler1D/sampler3D and texture1D/texture2D.

cheers,
Stephan

#3

I get in the console…

fragmentShader reports:
(2) warning c7508: extension GL_ARB_texture_rectangle not supported
(2) warning C7506: opengl does not define the global type samplerRECT
(5) error C1008: undefined variable “textureRECT”
(5) error C1105: cannot call a non-function

#4

[quote author=“chrisoshea”]I get in the console…

fragmentShader reports:
(2) warning c7508: extension GL_ARB_texture_rectangle not supported
(2) warning C7506: opengl does not define the global type samplerRECT
(5) error C1008: undefined variable “textureRECT”
(5) error C1105: cannot call a non-function

[/quote]

as noted, this was from my memory, try sampler2DRect / texture2DRect instead

cheers,
Stephan

#5

Nope, doesnt work. Same error.

Maybe my graphics card isn’t good enough.

Strange though, as I’ve downloaded lots of different compiled glsl and cg examples that work fine.

#6

What hardware are you using?

I tested the sampler2DRect / texture2DRect on my MacBookPro / OS X with GLSLEditorSample, and it worked,

cheers,
Stephan

#7

my graphics card is nvidia geforce go 7400.

updating to power book later this week.