Proper way to do texture mapping in modern OpenGL?

Question

I'm trying to do texture mapping using OpenGL 3.3 and GLSL 150.

The problem is the texture shows but has this weird flicker I can show a video here.

My texcords are in a vertex array. I have my fragment color set to the texture values and texel values. I have my vertex shader sending the texture cords to texture cordinates to be used in the fragment shader. I have my ins and outs setup and I still don't know what I'm missing that could be causing that flicker.

Here is my code:

Fragment shader

#version 150

uniform sampler2D texture;     
in vec2 texture_coord;

varying vec3 texture_coordinate;      
void main(void) {
    gl_FragColor = texture(texture, texture_coord);
}

Vertex shader

#version 150

in vec4 position;
out vec2 texture_coordinate; 
out vec2 texture_coord;
uniform vec3 translations;

void main() {    
    texture_coord = (texture_coordinate);
    gl_Position = vec4(position.xyz + translations.xyz, 1.0);  
}

Last bit

Here is my vertex array with texture coordinates:

GLfloat vVerts[] = {  
   0.5f, 0.5f, 0.0f, 0.0f, 1.0f,               
   0.0f, 0.5f, 0.0f, 1.0f, 1.0f,            
   0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 
   0.5f, 0.0f, 0.0f, 1.0f, 0.0f}; //tex x and y

If you need to see all the code, here is a link to every file.

Thank you for your help.

Answer 1

1. In your vertex shader, texture_coordinate is declared as an out variable, but you use it as if it were an input. You might be collecting trash data here. You meant it to be an attribute (deprecated in GLSL 1.50, that's just in for your vertex shader.) It's surprising you didn't get at least a warning (which you probably have but didn't notice, are you checking the error log?)

2. texture_coordinate and texture_coord are both vec2, but then in your fragment shader, texture_coordinate is a vec3, so types do not match.

3. varying is deprecated in GLSL 1.50 so I encourage you not to use it. It's inferred from the in/out qualifiers in each shader and the different interpolation qualifiers (smooth, flat and noperspective.)

There are several problems in your shader which seem to be the consequence of heavy copy-pasting from tutorials involving different GLSL versions. You might want to check GLSL 1.50 reference thoroughly and the error log to avoid these.