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Item GLRex(The Eurographics Association, 10-8-2006) McDonald, Gerard; -I first taught computer graphics programming on PCs in the late 1980s. We produced images with a few platonic solids in 256 colors. Real-time animation was out of the question. I remember writing programs for my classes to do ray-tracing and hidden surface removal that ran at glacial speed. Despite all the shortcomings, the students enjoyed the classes and the images they could create, even though they were relatively simple. Computer graphics was still something of a novelty, and producing any image for the computer to display was exciting. By the mid-1990s things had changed quite a bit. High-end graphics libraries like OpenGL had become available for the PC. Combining them with improvements in hardware (more memory, faster processors, better video cards), it was now possible to do relatively sophisticated graphics even on low-end PCs. At the same time students' expectations were rising as computer graphics became more pervasive in our culture. They are accustomed to seeing very sophisticated computer imagery in the games they play and the movies they watch. Students expect to be able to create visually exciting projects. But beginning students often find their creativity limited by the tedium of building scenes directly in code. GLRex is an attempt to address this problem. GLRex is a simple modeler that provides the user with interactive assistance in creating code for complex images. The user can create scenes with spheres, boxes, cylinders, and cones, as well as NURB surfaces of revolution and extrusion. These scenes may then be exported as OpenGL-based C programs (or RenderMan RIB files) to be used as a basis for more complex projects.Item Signal Convolution(The Eurographics Association, 9-7-2007) Hanisch, Frank; -This interactive teaching gem shows the convolution concept for continuous signals and discrete samples. Signals occurring frequently in computer graphics education are predefined; others can be drawn or integrated easily. We explain how the material can be used for in-class demonstration and for homework, and describe the experiences we made with two courses on image processing and introductionary computer graphics. Student reading is provided.Item ShaderSchool – A tutorial for shader programming(The Eurographics Association, 9-7-2007) Reimers, Ulf; Beckhaus, Steffi; Thiesen, Malte; -We present a tool for in-class and self-study learning that provides a convenient introduction into GLSL shader programming. The tool presents shaders in an interactive manner, and can be present in-class in a group interactive manner or used as an individual tutorial. In ShaderSchool the materials are presented in sections with interactive assignments integrated into the tool, which help reinforce the students learning. It was created and applied successfully in an university computer graphics class. Additionally, the ShaderSchool tool is extensible to easily incorporate further lessons. 1 IntroductionItem Marching Square(The Eurographics Association, 6-8-2004) Hanisch, Frank; -This interactive CGEM illustrates the marching squares algorithm, a 2D isoline representation technique commonly used for contouring. Teachers may also use this CGEM to introduce the 3D marching cubes algorithm, which uses the same approach [1]. Users can directly manipulate two circle objects. The shape of the objects is considered unknown. After sampling the objects on a regular grid, the marching squares algorithm approximates the contour. Users may move the circles to adjacent locations to experience how we resolve ambiguous cases by an additional midpoint test.Item Labs and Framework for 2D Content Manipulation(The Eurographics Association, 18-7-2006) Paquette, Eric; Barré-Brisebois, Colin; Barras, Jean-François; Bois, Frank Sébastien; Ghaouat, Mohammed El; -Creating and manipulating 2D content is important for computer scientists and requires knowledge in 2D Computer Graphics and Image Processing. A framework and five labs are proposed to help undergraduate students in Computer Science curricula to master the theory, algorithms, and data structures involved in 2D Computer Graphics and Image Processing. The labs provide a good coverage of topics, allow many alternatives, and can be easily reordered and selected to suit many types of courses. The framework has a working user interface to view and manipulate 2D content as well as adjust the parameters of the algorithms to implement. The framework also provides an architecture that hides most of the difficulties of the user interface and simplifies the implementation of the 2D content manipulation algorithms. Finally, code examples are provided to help the students in understanding how to use the framework to implement the labs.Item ShadowGui – An Interactive Shadow Tutorial(The Eurographics Association, 8-10-2007) Kuehl, Bjoern; Blom, Kristopher J.; Beckhaus, Steffi; -Today's mainstream computer graphics converges more and more to what was, in the past, possible only to do with expensive workstations. The addition of shaders to consumer graphic boards, which enable the usage of special effects like bump mapping and per pixel lighting, changed the look of today's computer graphics totally. One main effect, which makes the scene look more realistic, is shadows. It can help the viewer to understand the relative position of objects making the scene more believable. There are several common methods of making shadows, each of them having advantages and disadvantages. The two most popular methods are shadow mapping and stencil shadow volumes. In this tutorial, both shadow methods are explained two times. The first time, using only pure cpu-power, which makes the approaches slow, but they are easier to understand. Then, the tutorial explains how to use the power of today's graphic cards by outsourcing calculations to shaders. Because the shadow generation methods are implemented using OpenGL, previous knowledge about this graphics library is recommended, for example how to move objects by manipulating the glModelView matrix. However, all that must be known to calculate shadows will be explained in this tutorial.Item A Lab Exercise for 2D Line Clipping(The Eurographics Association, 9-7-2007) Stahl, David; -Line clipping is a fundamental topic in an introductory graphics course. The simplicity and elegance of the classic Cohen-Sutherland 2D Line Clipping Algorithm makes it suitable for implementation by the student in a lab exercise. An understanding of the algorithm is reinforced by having students write actual code and see the results. A code framework is provided that allows an instructor to focus student effort on the algorithm while avoiding the details of the visualization API used to render the results.