Try using gluLookAt glClearColor(0.0, 0.0, 0.0, 1.0); glClear(GL_COLOR_BUFFER_BIT); glMatrixMode(GL_PROJECTION); glLoadIdentity(); /* use this length so that camera is 1 unit away from origin */ double dist = sqrt(1 / 3.0); gluLookAt(dist, dist, dist, /* position of camera */ 0.0, 0.0, 0.0, /* where camera is pointing at */ 0.0, 1.0, 0.0); /* which direction is … Read more
The following code is based on a quaternion (qw, qx, qy, qz), where the order is based on the Boost quaternions: boost::math::quaternion<float> quaternion; float qw = quaternion.R_component_1(); float qx = quaternion.R_component_2(); float qy = quaternion.R_component_3(); float qz = quaternion.R_component_4(); First you have to normalize the quaternion: const float n = 1.0f/sqrt(qx*qx+qy*qy+qz*qz+qw*qw); qx *= n; qy … Read more
RESOLVED Here’s how to do it exactly, step by step. Obtain your mouse coordinates within the client area Get your Projection matrix and View matrix if no Model matrix required. Multiply Projection * View Inverse the results of multiplication Construct a vector4 consisting of x = mouseposition.x within a range of window x transform to … Read more
The OpenGL wiki gives a good definition: A Shader is a user-defined program designed to run on some stage of a graphics processor. History lesson In the past, graphics cards were non-programmable pieces of silicon which performed a set of fixed algorithms: inputs: 3D coordinates of triangles, their colors, light sources output: a 2D image … Read more
How can data not be 1-byte aligned? This strongly suggests a lack of understanding of what the row alignment in pixel transfer operations means. Image data that you pass to OpenGL is expected to be grouped into rows. Each row contains width number of pixels, with each pixel being the size as defined by the … Read more
Update (Sep. 17, 2017): NVIDIA recently published an article detailing how to use OpenGL on headless systems, which is a very similar use case as the question describes. In summary: Link to libOpenGL.so and libEGL.so instead of libGL.so. (Your linker options should therefore be -lOpenGL -lEGL Call eglGetDisplay, then eglInitialize to initialize EGL. Call eglChooseConfig … Read more
On Windows there is OpenGL extension method wglSwapIntervalEXT. From the post by b2b3 http://www.gamedev.net/community/forums/topic.asp?topic_id=360862: If you are working on Windows you have to use extensions to use wglSwapIntervalExt function. It is defined in wglext.h. You will also want to download glext.h file. In wglext file all entry points for Windows specific extensions are declared. All … Read more
Some of the terminology is a bit off: A Vertex Array is just an array (typically a float[]) that contains vertex data. It doesn’t need to be bound to anything. Not to be confused with a Vertex Array Object or VAO, which I will go over later A Buffer Object, commonly referred to as a … Read more
Sure, just use fig.canvas.tostring_rgb() to dump the rgb buffer to a string. Similarly, there’s fig.canvas.tostring_argb() if you need the alpha channel, as well. If you want to dump the buffer to a file, there’s fig.canvas.print_rgb and fig.canvas.print_rgba (or equivalently, print_raw, which is rgba). You’ll need to draw the figure before dumping the buffer with tostring*. … Read more
GL_POLYGON is only for convex polygons: GL_POLYGON: Draws a single, convex polygon. Vertices 1 through N define this polygon. For concave polygons you have at least two options: Triangulate the polygon and use GL_TRIANGLES. Use the stencil buffer trick.