Scaling Matrix in GLSL

[Niven]

I'm working on creating shaders to be used for displaying text in my openGL programs but am having trouble. I want to be able to scale the text but I don't want to use a uniform ( I want different strings of text to be able to be scaled differently ) so I'm using an in variable. I'm not sure how to use a VBO with a mat4 so instead i've been using a vec2 and trying to convert it to a mat4 in glsl before multiplying it with the position. The problem is that when I run my program, my text isn't scaled; it's just partially missing (the part that is there is about the same size). My vertex shader for this is:

#version 140

in vec2 Position;
in vec4 VertexColor;
in vec2 TexCoord;
in vec2 Scale;

out vec4 Color;
out vec2 UV;


void main()
{
    mat4 Scale_Matrix;
    for ( int x = 0; x < 4; x++ )
        for ( int y = 0; y < 4; y++ )
            if ( x == y && x < 2 )
                Scale_Matrix[x][y] = Scale[y];
            else if ( x == y )
                Scale_Matrix[x][y] = 1;
            else
                Scale_Matrix[x][y] = 0;

    gl_Position = Scale_Matrix * vec4( Position, 0, 1);

    UV = TexCoord;
    Color = VertexColor;
}

Also, correct me if I'm wrong but a scaling matrix should look like this:
| x, 0, 0, 0 |
| 0, y, 0, 0 |
| 0, 0, z, 0 |
| 0, 0, 0, 1 |
with z = 1 for 2d scaling, right?

[Disch]

The scaling matrix you're using is correct, and I don't see any obvious problems with the shader.

Can you post an image (like on tinypic or something) of the problem you're seeing?

[o1vk4iN6]

That matrix construction code is really ... yah you'd just be better off doing something like this:

mat4(mat2(scale[0],0,0,scale[1]))

Generally you want to avoid for loops as much as possible.

[Disch]

arguably he doesn't even need a matrix at all:

gl_Position = vec4( Position.x * Scale.x, Position.y * Scale.y, 0, 1 )

[Niven]

Since it doesn't look like the problem is with the shader, I'm gonna look at the my c++ code instead to see if I find any mistakes.

@Disch
I posted an image here: http://tinypic.com/r/2i08byr/5
@xerzi
I changed that in my shader know but nothings changed

Edit:
Nvm. I know what happened, it was a stupid mistake on my part. Among other things, the problem was caused by the positioning of the text, and how the handled the coordinates before sending them to the shader.