How to get texture coordinate to GLSL in version 150? - glsl

Question

In GLSL version 110 i can get coordinate in gl_TexCoord[] but it's deprecated in 150.
OpenGL code:
shader.setupShaderFromFile(GL_VERTEX_SHADER, "t.vert");
shader.setupShaderFromFile(GL_FRAGMENT_SHADER, "t.frag");
shader.linkProgram();
glGetFloatv(GL_MODELVIEW_MATRIX, modelview_mat_);
glGetFloatv(GL_PROJECTION_MATRIX, projectionview_mat_);
shader.begin();
glUniformMatrix4fv( glGetUniformLocation(shader.getProgram(), "MVMatrix"), 1, GL_FALSE, modelview_mat_);
glUniformMatrix4fv( glGetUniformLocation(shader.getProgram(), "MPMatrix"), 1, GL_FALSE, projectionview_mat_);
glBegin(GL_QUADS);
glTexCoord2f(0, 0);glVertex2f(0, 0);
glTexCoord2f(1, 0);glVertex2f(100, 0);
glTexCoord2f(1, 1);glVertex2f(100, 100);
glTexCoord2f(0, 1);glVertex2f(0, 100);
glEnd();
shader.end();
Shader Code:
VERTEX-
#version 150
in vec3 in_vertex;
in vec2 in_coord;
uniform mat4 MVMatrix;
uniform mat4 MPMatrix;
out vec2 tex_coord;
void main()
{
vec4 v = vec4( in_vertex, 1.0 );
tex_coord = in_coord;
gl_Position = MPMatrix * MVMatrix * v;
}
FRAGMENT:
#version 150
in vec2 tex_coord;
out vec4 frgcolor;
void main()
{
frgcolor = vec4( tex_coord, 0.0, 1.0);
}
final screen is a red quad.
How to pass texture coordinate to shader? or my code is wrong?

Answer 1

If you don't want to use the deprecated methods, you'll have to stop using glTexCoord2f, and use a custom attribute.
If you want to stay with immediate mode, you'll use glVertexAttrib2f.
You pair this up with your new variable 'in_coord' by quering the index after shader linking:
int program = glCreateProgram();
//create shader as normal
int texcoord_index = glGetAttribLocation(program, "in_coord");
glBegin(GL_QUADS);
glVertexAttrib2f(texcoord_index, 0, 0); ...
If you want to use VA/VBO instead, the functions you use instead is glEnableVertexAttribArray/glVertexAttribPointer

Answer 2

in your case just look into gl_TexCoord[0] in your vertex shader. Definitely works with shader model 1.5
in C++:
glActiveTexture(GL_TEXTURE0 );
glBindTexture(GL_TEXTURE_2D, id);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glBegin(GL_QUADS);
glTexCoord2f(0, 0);glVertex2f(0, 0);
glTexCoord2f(1, 0);glVertex2f(100, 0);
glTexCoord2f(1, 1);glVertex2f(100, 100);
glTexCoord2f(0, 1);glVertex2f(0, 100);
glEnd();
in vertex shader:
gl_TexCoord[0]=gl_MultiTexCoord0;
in fragment shader:
vec4 c = texture2D(texSampler, gl_TexCoord[0].st );