OpenGL(2.1) shader program not running, using color from glColor instead - c++

Question

I am working on an OpenGL 2.1 application, and trying to shift code from fixed to programmable pipeline piece by piece(i.e deprecated functions (glVertex*, glColor* etc) calls to buffers/shaders ).
The problem is color I set for each fragment from inside the fragment shader is not being set, instead it automatically paints fragment with color specified in last glColor3f call (which is somewhere else in the codebase, completely unrelated to piece of code at hand).
My vert/frag shaders are pretty straightforward :
#version 120
attribute vec3 position;
attribute vec3 color;
varying vec3 Color;
void main()
{
mat4 scaleMat = mat4(0.1,0,0,0,0,0.1,0,0,0,0,0.1,0,0,0,0,1);
Color = color;
//gl_Position = scaleMat * vec4(position,1.0); //scaling doesn't have effect!
gl_Position = vec4(position, 1.0);
}
and
#version 120
varying vec3 Color;
void main()
{
//gl_FragColor = vec4(0.3,0.3,1.0,1.0); //Const color does not work.
gl_FragColor = vec4(Color,1.0); //taking interpolated color doesn't work either!
}
One more thing, you may notice I applied a scaling matrix in vertex shader to make geometry 10x smaller, but it does not have any effect! Which makes me wonder whether the shader is even 'doing its thing' or not. Because if I don't write the shader correctly, I get compile errors(duh.)
I'm using Qt, below is the code used for setting up buffers and shaderprogram.
void myObject::init()
{
//Shader related code. 'shader' is QGLShaderProgram object
shader.addShaderFromSourceFile(QGLShader::Vertex,
":/shaders/mainshader.vert");
shader.addShaderFromSourceFile(QGLShader::Fragment,
":/shaders/mainshader.frag");
shader.link();
shader.bind();
vertexLocation = shader.attributeLocation("position");
colorLocation = shader.attributeLocation("color");
.......
//bathBuffer and colorBuffer are QGLBuffer objects,
//triList is a vector<vec3> containing triangle data
bathBuffer.create();
bathBuffer.bind();
bathBuffer.setUsagePattern(QGLBuffer::StaticDraw);
bathBuffer.allocate(sizeof(triList));
bathBuffer.write(0,triList.data(),sizeof(triList));
for(int i=0;i<triList.size();++i)
{
colorList.push_back(Vec(1,1,0));
}
colorBuffer.create();
colorBuffer.bind();
colorBuffer.setUsagePattern(QGLBuffer::StaticDraw);
colorBuffer.allocate(sizeof(colorList));
colorBuffer.write(0,colorList.data(),sizeof(colorList));
//copies both color and vert data
}
and here's the draw() function:
void myObject::draw()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
shader.bind();
bathBuffer.bind();
shader.enableAttributeArray(vertexLocation);
shader.setAttributeArray(vertexLocation,GL_DOUBLE,triList.data(),3,0);
colorBuffer.bind();
shader.enableAttributeArray(colorLocation);
shader.setAttributeArray(colorLocation,GL_DOUBLE,colorList.data(),3,0);
glDrawArrays(GL_TRIANGLES, 0, triList.size());
shader.disableAttributeArray(vertexLocation);
shader.disableAttributeArray(colorLocation);
//shader.release();
}
I even tried to use a GL profiler to figure out what might be going wrong beneath all the abstraction:
As you can see, glCreateProgram() returns 1, but trying to glUseProgram returns error saying Program handle does not refer to an object generated by opengl. Like wtf.
Then I thought it might be some Qt thing where it might be making a buggy context from the start, so I added this code to my main.cpp as well, just to make sure we get correct context.
QGLFormat f;
f.setOption(QGL::DeprecatedFunctions| QGL::DepthBuffer | QGL::DoubleBuffer | QGL::Rgba | QGL::AlphaChannel);
f.setVersion(2,1);
QGLContext ogl_context(f);
ogl_context.create();
ogl_context.makeCurrent();
....to no avail.
tldr;
I'm not sure whether the shaders are working or not
Is there a way to ignore/'switch off' glColor calls so that I paint geometry from within shaders itself?
I have run out of options to think of. I can provide more info if needed. Any help on this would be appreciated.
Thanks.
EDIT: Whole class relevant to this question: bathymetry.h , bathymetry.cpp . I have added the whole class relevant to this question. Other code is a custom widget class(not doing any opengl stuff) that handles the Qt part and a main.cpp.