[PD] [GEM]: how to alpha blend gradually

[cyrille henry]

Kyle Klipowicz a écrit :
> Thanks, cyrille. I know virtually nothing of OpenGL other than what
> I've learned from using Gem.
> 
> Is there any tutorial on implementing pixel shaders in Gem?

there is an exemple in the gem doc : 
2.advence/18.gl_sading_language.pd
this is how to load a shader with gem.
for generic informations about how to write a shader, you have to find a good book.
like the openGL shading Language by Randy Rost.


cyrille.
 
> 
> ~Kyle
> 
> On 6/16/07, cyrille henry <cyrille.henry at la-kitchen.fr> wrote:
>> Hello,
>>
>> As Chris says, a shader is fine, but you can also do it with older 
>> opengl stuff.
>> like in this patch.
>>
>> cyrille
>>
>> Max Neupert a écrit :
>> > hi list,
>> >
>> > how do i make a pix_film with a linear gradiation transparent (from
>> > left to right?)
>> >
>> > thank you
>> >
>> >
>> > max
>> >
>> > _______________________________________________
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>> >
>>
>> #N canvas 722 102 685 608 10;
>> #X obj 62 32 gemhead;
>> #X obj 62 72 pix_image;
>> #X obj 62 109 pix_texture;
>> #X obj 197 136 GLdefine GL_SMOOTH;
>> #X obj 61 202 GEMglBegin;
>> #X obj 61 160 GEMglShadeModel;
>> #X obj 61 137 alpha;
>> #X obj 73 397 GEMglColor4f 1 1 1 1;
>> #X obj 69 520 GEMglEnd;
>> #X obj 62 224 GEMglNormal3f 0 0 1;
>> #X obj 67 254 GEMglColor4f 1 1 1 0;
>> #X obj 67 309 GEMglVertex3f -4 -3 0;
>> #X obj 67 365 GEMglVertex3f -4 3 0;
>> #X obj 65 451 GEMglVertex3f 4 3 0;
>> #X obj 212 119 bng 15 250 50 0 empty empty empty 17 7 0 10 -262144
>> -1 -1;
>> #X obj 212 98 loadbang;
>> #X obj 60 9 tgl 15 0 empty empty empty 17 7 0 10 -262144 -1 -1 0 1
>> ;
>> #X obj 68 335 GEMglTexCoord2sv;
>> #X msg 423 19 color 1 0 0;
>> #X obj 69 497 GEMglVertex3f 4 -3 0;
>> #X obj 197 178 GLdefine GL_QUADS;
>> #X obj 66 280 GEMglTexCoord2sv;
>> #X obj 73 424 GEMglTexCoord2sv;
>> #X obj 69 473 GEMglTexCoord2sv;
>> #X msg 253 230 0 0;
>> #X msg 257 276 0 300;
>> #X msg 266 316 400 300;
>> #X msg 278 352 400 0;
>> #X text 339 285 <- change to images pixel size;
>> #X msg 148 80 mode 1;
>> #X obj 206 4 bng 15 250 50 0 empty empty empty 17 7 0 10 -262144 -1
>> -1;
>> #X obj 204 33 openpanel;
>> #X msg 204 62 open \$1;
>> #X obj 408 167 gemwin;
>> #X msg 443 95 create \, 1;
>> #X connect 0 0 1 0;
>> #X connect 1 0 2 0;
>> #X connect 2 0 6 0;
>> #X connect 3 0 5 1;
>> #X connect 4 0 9 0;
>> #X connect 5 0 4 0;
>> #X connect 6 0 5 0;
>> #X connect 7 0 22 0;
>> #X connect 9 0 10 0;
>> #X connect 10 0 21 0;
>> #X connect 11 0 17 0;
>> #X connect 12 0 7 0;
>> #X connect 13 0 23 0;
>> #X connect 14 0 3 0;
>> #X connect 14 0 20 0;
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>> #X connect 19 0 8 0;
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>> #X connect 23 0 19 0;
>> #X connect 24 0 21 1;
>> #X connect 25 0 17 1;
>> #X connect 26 0 22 1;
>> #X connect 27 0 23 1;
>> #X connect 29 0 2 0;
>> #X connect 30 0 31 0;
>> #X connect 31 0 32 0;
>> #X connect 32 0 1 0;
>> #X connect 34 0 33 0;
>>
>> _______________________________________________
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>>
> 
>