@saket
I think the driver of your graphics card isn't able to understand the GLSL command. As i see you're using an Intel Graphics Card, i had a lot of problems with my GLSL code on several machines with Intel Graphics.

Try to change the attributes and varying qualifiers:

static const char *vertexShaderSource = "#version 140\n" "in vec4 posAttr;\n" "in vec4 colAttr;\n" "out vec4 col;\n" "uniform mat4 matrix;\n" "void main() {\n" " col = vec4(1, 0, 0, 1);\n" " gl_Position = matrix * posAttr;\n" "}\n"; static const char *fragmentShaderSource = "#version 140\n" "in vec4 col;\n" "out vec4 fragcol;\n" "void main() {\n" " //gl_FragColor = col;\n" " fragcol = col;\n" "}\n";

And try to get the Info from the shader after compilation (https://www.opengl.org/wiki/Shader_Compilation#Shader_error_handling)

GLuint shader = glCreateShader(...); // Get strings for glShaderSource. glShaderSource(shader, ...); glCompileShader(shader); GLint isCompiled = 0; glGetShaderiv(shader, GL_COMPILE_STATUS, &isCompiled); if(isCompiled == GL_FALSE) { GLint maxLength = 0; glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &maxLength); // The maxLength includes the NULL character std::vector<GLchar> errorLog(maxLength); glGetShaderInfoLog(shader, maxLength, &maxLength, &errorLog[0]); // Provide the infolog in whatever manor you deem best. // Exit with failure. glDeleteShader(shader); // Don't leak the shader. return; } // Shader compilation is successful.