GL Shading Language problem
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In GLSL, is that gl_TexCoord[0] means indexing the present texture coordinate that is working on?
Also, for gl_TexCoord[0].st, what does .st means?
gl_TexCoord[0] means get the texture coordinate for the first texture unit (GL_TEXTURE0). When multi-texturing (more than one texture at time) you could enable multiple textures units, so you could have gl_TexCoord[1] for the second texture unit ...
example in the C++ you have:
glActiveTextureARB(GL_TEXTURE0_ARB);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, num);
glTexCoord2f(8,5) ;
then you get the TexCoord in your GLSL:
gl_TexCoord[0].s ; // = 8
gl_TexCoord[0].t ; // = 5
By default only one texture unit is enable (if you glEnable(GL_TEXTURE_2D); ) which is GL_TEXTURE0
example in the C++ you have:
glActiveTextureARB(GL_TEXTURE0_ARB);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, num);
glTexCoord2f(8,5) ;
then you get the TexCoord in your GLSL:
gl_TexCoord[0].s ; // = 8
gl_TexCoord[0].t ; // = 5
By default only one texture unit is enable (if you glEnable(GL_TEXTURE_2D); ) which is GL_TEXTURE0
gl_TexCoord[0] refers to the coordinates of the 0th texture unit.
.st is used to smear the vector. It means, you are aceesing/assigning only 2 (s & t) components of the vector depending on the usage of it vector.
.st is used to smear the vector. It means, you are aceesing/assigning only 2 (s & t) components of the vector depending on the usage of it vector.
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