Assignment 1 OpenGL Basics Total Number of Points for this Assignment 15 In this programming assignment you will be required to write a program to render polygonal meshes For this you will need to practice about some important features of a graphics application and their implementation using OpenGL and Shader functions For example you will know how to Specify a virtual camera with arbitrary position and orientation Render an object using different kinds of primitives such as points wireframe and solid polygons Perform back face culling to reduce the number of primitives actually drawn Change the field of view of the camera to achieve some zooming effects Besides supporting all the features listed above your program should be able to 1 Read and display arbitrary geometric models represented as triangle meshes These objects are described in obj suffix format see Appendix II The obj file is a standard data format that represents 3D geometry Models are already provided in the objs folder in the starter code You can also download them from eLearning Once you read these objects they should be displayed in the center of the window 3 points 2 Translate the virtual camera along its own axes u v n not along the world coordinate 3 Rotate the virtual camera along its own axes 2 points 4 Reset the camera to its original position i e object centered inside the window 1 system axes 2 points point 5 Support or rendering objects whose polygon vertices were defined using CW clockwise and CCW counter clockwise orientation this will affect the behavior of the back face culling procedure 1 point 6 Support for changing the values of the near and far clipping planes 1 point 7 Support for interactive change of colors R G B for the models making sure that the color change is clear for all rendering modes No lighting required for this assignment yes it s assignment 2 A single RGB color is assigned to all triangles of the model 2 points 8 Support for rendering the object using different kinds of primitives such as points wireframe and solid polygons 2 points 9 Support for reading a new model file through the user interface 1 point Submit your source code and a self contained executable file You will need to demonstrate your program to the instructor Please sign up your demo time in the following doodle https doodle com poll 66uttm4yfwi68qvp Appendix I Tips on How to Complete the Assignment Read the starter code carefully if you do not know how to start The starter code mentioned in the OpenGL Environment Setup folder has provided an overall structure with comments TODO to help you with all assignments Also you may find the free online OpenGL tutorials e g https learnopengl com Introduction could solve most of your OpenGL questions Don t use fixed rendering pipeline In our assignment you need to use the modern OpenGL rendering pipeline instead of fixed pipeline For example you should use glm perspective returning a mat and send mat into vertex shader instead of using gluperspective You should also not use glRotate glTranslate etc Rendering the object in the center of the window In order to render the object in the center of the window you will need to do some calculations For instance as you read the object description from the file given the vertices coordinates in WCS the object might be behind the camera or outside of its field of view It could also be too big and be only partially inside the view frustum You will then need to reposition the camera in order to make sure the object will be completely visible and centered in the window In order to accomplish this you will need to identify the range minimum and maximum coordinates of the object in both X Y and Z With these values at hand you can then imagine a bounding box a parallelepiped for the object In order for the object to appear centered the x and y coordinates for the position of the camera can be computed as the average of the corresponding min and max values Note however this might not be enough if the object is too big or if the field of view is too small In these cases the object might be partially outside of the view frustum You should then use your trigonometric skills to figure out what should be the z coordinate of the camera so that the object is completely visible and as close as possible Rotating the Camera In order to perform camera rotation translation around along the camera s axes you will need to keep track of the vectors that define the camera coordinate system As you start your program let these vectors be u 1 0 0 v 0 1 0 and n 0 0 1 As we rotate the camera we change the vectors that define the CCS note that this does not happen when we perform just a translation Thus we need to recalculate them Fortunately this is not difficult and can be accomplished using the same basic ideas used to derive the rotations of points in 2D and 3D Changing the values of the near and far clipping planes This can be accomplished with glm perspective Don t forget to select and initialize the projection matrix before you call glm perspective and to set the current matrix back to the model view matrix after you are done Initialize Znear 1 0f and Zfar 3000 0 and play with these values What happens when Znear becomes very close to zero Selecting the orientation CW CCW for the front facing polygons Your program should support change of the orientation interactively For this use the command glFrontFace Appendix II Layout of the obj file Command Vertex position v position x position y position z Vertex normal vn normal x normal y normal z Texture coordinate vt tu tv f v vt vn v vt vn v vt vn Faces are stored as a series of three vertices in clockwise order Vertices are described by their position optional texture coordinate and optional normal encoded as indices into the respective component lists We do not use in the first assignment Token v x y z float vn x y z float vt x y float f v1 vt1 vn1 v2 vt2 vn2 v3 vt3 vn3 int Other tokens Example cube obj v 0 500000 0 500000 0 500000 v 0 500000 0 500000 0 500000 v 0 500000 0 500000 0 500000 v 0 500000 0 500000 0 500000 v 0 500000 0 500000 0 500000 v 0 500000 0 500000 0 500000 v 0 500000 0 500000 0 500000 v 0 500000 0 500000 0 500000 vt 0 000000 0 000000 vt 1 000000 0 000000 vt 0 000000 1 000000 vt 1 000000 1 000000 vn 0 000000 0 000000 1 000000 vn 0 000000 1 000000 0 000000 vn 0 000000 0 000000 1 000000 vn 0 000000 1 000000 0 000000 vn 1 000000 0 000000 0 000000 vn 1 000000 0 000000 0 000000 f 1 1 1 2 2 1 …