OK, what else can it be?
I tried the new nvidia drivers and another graphics card. Both gave the
same unchanged results.
I'm using multitextures. Can it be, that I'm accessing another textures,
and not that one, I want to access?
But I'm not changing anything in my application, I only change the data
of the image.
But the failure is still there!
And by the ways, I'm searching for another solution. How can I use 64bit
floating point textures. I want to create them, access them in the
shader and render the result to a render target. I know, that I cannot
use the framebuffer, but what can I use instead? I wonder, if I can use
the OpenSG Image Objects for creating 64bit textures?
bye
Oliver
Dirk Reiners schrieb:
Hi Oliver,
On Thu, 2005-08-18 at 19:27 +0200, Oliver Kutter wrote:
Hello World ;-) ,
I have a problem with accessing textures in my fragment shader program.
I want to access the texture, but not at the fragment's current
position. Normally, the program looks up the texture at the specified
fragment texture coordinates stored in gl_TexCoords[0]. But I want to
get texture values from other coordinates.
Example:
Normal you do:
vec4 myFragColor = texture2D (myTexture, vec2 (gl_TexCoords[0]));
gl_FragColor = myFragColor;
But I want to do:
float texSize = 256.0;
float x = xpos / texSize;
float y = ypos / texSize;
vec4 myFragColor = texture2D (myTexture, vec2 (x, y));
gl_FragColor = myFragColor;
Now my Problem:
When I choose xpos and ypos as fixed values (e.g. xpos = 50.0, ypos =
100.0), I have no problem. I get exactly the color at the specified
coordinates (50,100) in the texture.
But when I choose xpos and ypos to be variable (what I want to achieve),
I get everytime, when I start my application, different color values.
The funny thing is, that I have everytime the same (correct) texture
coordinates. Sometimes I get the correct color values, but mostly I get
the wrong values.
I tested it with the following code (I can take x and y as color values):
gl_FragColor = vec4 (myFragColor.x, x, y, 1.0);
Has anyone an idea?
That sounds reasonable and simple. Have you tried running it on a
different graphics card/driver combo? GLSL is still not as stable as it
should be, even though your example is simple enough that I wouldn't
expect it to be a problem.
Yours
Dirk
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