ASSIGNMENT 2 VIEWING, LIGHTING AND TEXTURING G53GRA Computer Graphics 9th March 2017 This assignment is compulsory and worth 15% of your final mark for this module. It is due for submission by 3pm Thursday 30th March 2017. Submission should be made via Moodle. Late submissions will receive a penalty of 5% of the assignment grade per working day. Files must be submitted in .zip or .pdf format and contain both answers to the questions and your code. Please provide screen shots embedded into your answers document or as separate image files in your .zip file. The assignment is based on lectures 5–8, and covers viewing, lighting and texturing. All questions have equal weighting and are each worth 20% of the assignment. 1 Transformation in Camera Space y z x v u n eye (du,dv,dn) Suppose in a graphics program, the camera/eye is positioned at p = (10, 10, 10) in world space. The camera's coordinate axes are defined as follows: u = (1, −1, 1) v = (1, 1, 0) n = (0.5, −0.5, −1) Where u is the right vector of the camera, v the up vector, and n is the viewing direction. Calculate the new position of the camera, p0 after a transformation in camera space is applied, such that its position is translated by du = 2 along u, dv = 1 along v and dn = −1 along n. You must show your complete working. Assignment 2: Viewing, Lighting and Texturing 12 Projection and Hidden Surface Removal Describe the processes involved in projecting 3D graphics objects onto a 2D screen, using both orthographic and perspective projection. Describe the process of face culling, and explain how OpenGL determines which surfaces are hidden in a 3D scene. 3 Light Reflection Models Describe the individual components of the Phong reflection model and how they are combined to create a final lit scene. Describe how the light, viewing direction and surface normal affect the light intensity at a point on the surface of an object. Note: Do not confuse the Phong reflection model with Phong interpolation shading. 4 Programming Exercise: Wall Lights light a light b Use OpenGL commands and freeglut to model two lights on a planar "wall". You should render a wall that is perpendicular to the view direction (such that you can see the wall straight on), and two positional light sources in front of or on the wall plane. The light sources should use different diffuse lighting colour, and have non-constant attenuation (reduction intensity with distance from source). The diagram is a basic demonstration of what your program should produce. Your lighting scene need not strictly match the appearance of this diagram – it is largely for reference. Note: You may find the Floor class from the Viewing Example demo helpful. Note: You do not need to visualise your light sources as objects for the assessment, but you may find it useful as a location reference. Assignment 2: Viewing, Lighting and Texturing 25 Programming Exercise: Texture Blending Extend the Textured Sphere demo to combine the two bitmap images using OpenGL blending, as shown in the diagram. You should use glBlendFunc(), and state which blending function you have used and explain why. The textures can be downloaded here. The demo branch for the Textured Sphere is available here. Note: You only need to submit your new BlendedSphere object code, rather than the whole project. Note: Do not combine the textures in photo editing software. Assignment 2: Viewing, Lighting and Texturing 3