Rendering a texture in openGL with Qt5 and glew - qt

Question

I am trying to render a textured quad in openGL using Qt5 and glew.
specifically I am using a QopenGLWidget.
The code I am using is modified from https://open.gl/textures
The main changes are using a triangle strip instead of an elements buffer
and using my own pixel array instead of loading an image.
I have tested changes and they work using glfw3.
In Qt all I can see is a black quad with no colour.
This only occurs when I try to use textures, it renders colours fine if i remove the texture part of the shader.
My shaders compile fine with no errors (although there is no error checking in the code below).
texture(tex, Texcoord)
is just outputting zero.
So my question is, why is it rendering just a black quad?
GLfloat tmpdata[] = {
//pos //colour //texCoord
-0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, // Top-left
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // Top-right
-0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, // Bottom-left
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f // Bottom-right
};
GLRenderer::GLRenderer(QWidget *parent)
:
QOpenGLWidget(parent)
{
// Shader sources
VertSource =
"#version 150 core\n"
"in vec2 position;"
"in vec3 color;"
"in vec2 texcoord;"
"out vec3 Color;"
"out vec2 Texcoord;"
"void main() {"
" Color = color;"
" Texcoord = texcoord;"
" gl_Position = vec4(position, 0.0, 1.0);"
"}";
FragSource =
"#version 150 core\n"
"in vec3 Color;"
"in vec2 Texcoord;"
"out vec4 outColor;"
"uniform sampler2D tex;"
"void main() {"
" outColor = texture(tex, Texcoord) * vec4(Color, 1.0);"
// " outColor = vec4(Color, 1.0);"
//" outColor = texture(tex, Texcoord);"
"}";
}
GLRenderer::~GLRenderer()
{
glDeleteProgram(shaderProgram);
glDeleteShader(fragmentShader);
glDeleteShader(vertexShader);
glDeleteBuffers(1, &vbo);
glDeleteVertexArrays(1, &vao);
}
void GLRenderer::initializeGL()
{
glewExperimental = GL_TRUE;
GLenum err = glewInit();
if (err != GLEW_OK)
{
printf("%s", glewGetErrorString(err));
}
// Create Vertex Array Object
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
// Create a Vertex Buffer Object and copy the vertex data to it
GLuint vbo;
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(tmpdata), tmpdata, GL_STATIC_DRAW);
// Create and compile the vertex shader
GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &VertSource, NULL);
glCompileShader(vertexShader);
// Create and compile the fragment shader
GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &FragSource, NULL);
glCompileShader(fragmentShader);
// Link the vertex and fragment shader into a shader program
GLuint shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glBindFragDataLocation(shaderProgram, 0, "outColor");
glLinkProgram(shaderProgram);
glUseProgram(shaderProgram);
// Specify the layout of the vertex data
GLint posAttrib = glGetAttribLocation(shaderProgram, "position");
glEnableVertexAttribArray(posAttrib);
glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE, 7 * sizeof(GLfloat), 0);
GLint colAttrib = glGetAttribLocation(shaderProgram, "color");
glEnableVertexAttribArray(colAttrib);
glVertexAttribPointer(colAttrib, 3, GL_FLOAT, GL_FALSE, 7 * sizeof(GLfloat), (void*)(2 * sizeof(GLfloat)));
GLint texAttrib = glGetAttribLocation(shaderProgram, "texcoord");
glEnableVertexAttribArray(texAttrib);
glVertexAttribPointer(texAttrib, 2, GL_FLOAT, GL_FALSE, 7 * sizeof(GLfloat), (void*)(5 * sizeof(GLfloat)));
// Load texture
GLuint tex;
glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_2D, tex);
// Black/white checkerboard
float pixels[] = {
1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f,
0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f
};
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 2, 2, 0, GL_RGB, GL_FLOAT, pixels);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
}
void GLRenderer::paintGL()
{
// Clear the screen to black
glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}