Hi,
I guess if I had a deep understanding of openGL I could find the answer,
but I am obviously looking for a shortcut (at the moment) to solve the
specific problem I'm facing which should be pretty simple.
In the attached patch I try to use a trivial shader to texture a
rectangle with an image; the uniform variable "curtex" tells the shader
which texture to use.
It works fine if all images have the same size; however, if the textures
have different sizes, no matter the value of "curtex", the texture
coords that are computed are correct for the image loaded by the
[pix_image] that immediately follows the [glsl_program], but are not
correct for other images.
So the question is: how should I change the vertex and/or fragment
shader code (or the patch maybe) so that the texture coordinates are
computed according to the dimensions of the texture that is actually
sampled?
It is important to NOT assume that the textures come from [pix_image]
objects, or at least, that they are loaded from image files: actually,
in real life, textures may be the video input generated by a [pix_film]
or an image captured by a [pix_snap].
Thanks a lot in advance
--
Matteo Sisti Sette
matteosistise...@gmail.com
http://www.matteosistisette.com
// porcodio
#extension GL_ARB_texture_rectangle : enable
uniform sampler2DRect curtex;
void main (void)
{
vec2 xy=gl_TexCoord[0].st;
vec4 frontcolor = texture2DRect(curtex, xy);
gl_FragColor = frontcolor;
}
#N canvas 443 93 925 656 12;
#X obj 441 576 gemwin;
#X msg 437 515 create \, 1;
#X msg 484 547 destroy;
#X obj 58 177 glsl_vertex;
#X obj 59 313 glsl_fragment;
#X obj 143 211 change;
#X obj 160 342 change;
#X obj 155 385 t b f;
#X obj 153 418 pack 0 0;
#X obj 60 490 glsl_program;
#X msg 154 454 link \$1 \$2;
#X obj 60 567 pix_texture;
#X obj 188 24 bng 15 250 50 0 empty empty empty 17 7 0 10 -262144 -1
-1;
#X obj 69 33 gemhead 50;
#X obj 508 77 gemhead 23;
#X obj 511 259 pix_texture;
#X msg 519 221 texunit 1;
#X obj 664 260 pix_texture;
#X obj 661 78 gemhead 24;
#X floatatom 212 525 5 0 0 0 - - -;
#X obj 70 60 t a a;
#X msg 349 409 rectangle 1;
#X obj 348 384 loadbang;
#X msg 757 119 rectangle 1;
#X obj 762 53 loadbang;
#X msg 136 99 open trivialshader.vert;
#X msg 114 259 open trivialshader.frag;
#X obj 60 600 square 4;
#X obj 46 528 pix_image img1_.jpg;
#X obj 506 163 pix_image img2_.jpg;
#X obj 659 164 pix_image img3_.jpg;
#X msg 278 474 texunit 2;
#X msg 672 222 texunit 0;
#X floatatom 253 333 5 0 0 0 - - -;
#X msg 229 387 curtex \$1;
#X connect 1 0 0 0;
#X connect 2 0 0 0;
#X connect 3 0 4 0;
#X connect 3 1 5 0;
#X connect 4 0 9 0;
#X connect 4 1 6 0;
#X connect 5 0 8 0;
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#X connect 9 0 28 0;
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#X connect 34 0 9 0;
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