hi everybody, i am just seeking a little hint. I have been studing the per vertex and per fragment programs for a month now, and i think i am beginning to understand the whole thing a little more now. Now that i have a little understanding on the argument i would like to know what kind of shader language should be the most useful to learn. For what i can see i have 2 choices (and half). Should I learn assembly like programs used with GL_*_PROGRAM_ARB, or the c like OGSL shaders? The half choice should ne NVidia''s CG, but as for now i''d prefer a cross platform language, so i won''t consider studing a card specific shading method. Does someone knows what shading language will use OpenGL 2? It would be nice to study something that WON''T get obsolete in the next few months... thanks for the help, the Gunslinger...

probably is just a wrong guess from mine...
Anyway since it lost the contest for opengl 2 shading language i think that it would be more useful concentrating on more supported per fragment tecniques.

trivial discussion, my simple shader isn''t just working
it is just displayng blank screen :|
Hope to hear from you soon, bye!

no cg, sorry, i am fling low in assembler, as for now.
i am using 2 simple programs, my vertex program is working fine (at least if i enable just that one my OpenGL app displays the right things.
The fragment program on the other hand isn''t working at all, if it is enabled, it just clears the window to a depressing BLACK.

the fragment program code is:

!!ARBfp1.0

# Fragment inputs
ATTRIB inTexCoord = fragment.texcoord; # First set of texture coordinates
ATTRIB inColor = fragment.color.primary; # Diffuse interpolated color

# Fragment outputs
OUTPUT outColor = result.color;

TEMP texelColor;
TXP texelColor, inTexCoord, texture, 2D;

MUL outColor, texelColor, inColor; # Modulate texel color with vertex color
#ADD outColor, texelColor, inColor; # Add texel color to vertex color

END

Actually i am using no texture, but everybody told me that i have to specify TexCoords anyway (i think they are used to calculate the fragment interpoled color).
Hear from you soon,
Gunslinger

quote:Original post by gunslinger77
MUL outColor, texelColor, inColor; # Modulate texel color with vertex color

quote:
Actually i am using no texture, but everybody told me that i have to specify TexCoords anyway (i think they are used to calculate the fragment interpoled color).

Well, they told you wrong. And this is also where your problem lies: you are multiplying the vertex colour with the *texture* colour in your FP. If you don''t bind a texture, then the result will obviously be black.

Try this instead of the MUL: MOV outColor, inColor;

Oh yes, and you do realize, that you are actually doing a *projected* texture access ? I don''t think this is what you want. You would want to use TEX instead of TXP, assuming a valid texture is bound. Yep, those are the little problems when simply copy''n''pasting sample code from the specs without thoroughfully understanding it..

thank you anonymous
post after post i am seeing the light after all...

can you (or anybody else) explain what difference there is between tecture coordinates and projected texture coordinates? (TEX vs TXP...)
thx gunslinger