12.4: OpenGL 1.1 Examples

OpenGL 1.1 is the topic of Chapter 3 and Chapter 4. Examples in those chapters primarily use the C API for OpenGL. However, the Java API, JOGL, is also discussed. Most program examples are available in both the C and the Java APIs. The JOGL versions can be found in the directory named jogl inside the source directory. The C versions, which use the GLUT library to create and manage OpenGL windows, can be found in the directory named glut inside source. (Many of these programs use a “camera” API defined in jogl/Camera.java for Java and in glut/camera.c and glut/camera.h for C.)

The OpenGL demos in the book are written using glsim.js, a JavaScript library that implements a small subset of the C API for OpenGL 1.1. Information about glsim can be found in glsim/glsim-doc.html. Some of the program examples are available in HTML versions that use the glsim library. They can be found in the glsim directory inside source.

• glut/first-triangle.c, jogl/FirstTriangle.java and glsim/first-triangle.html are C, Java, and JavaScript versions of the very first OpenGL example: a triangle whose vertices are as- signed the colors red, green, and blue. You can use this example as a starting point for trying out some basic 2D drawing commands. From Section 3.1.
• glut/unlit-cube.c, jogl/UnlitCube.java, and glsim/unlit-cube.html are C, Java, and JavaScript versions of a program that draws a cube using modeling transformations ap- plied to a square. There is no lighting in this program, and it uses a basic orthographic projection, so the image is not realistic. From Section 3.2.
• glut/opengl-cart-and-windmill-2d.c (for C), jogl/CartAndWindmillJogl2D.java (for Java), and glsim/opengl-cart-and-windmill.html (for JavaScript) are versions of an example of hierarchical modeling and animation in two dimensions with OpenGL 1.1. It illustrates 2D graphics in OpenGL as well as the use of glPushMatrix and glPopMatrix for hierarchical modeling. The animation is almost the same as the one implemented in the Java Graphics2D example java2d/HierarchicalModeling2D.java and in the HTML canvas graphics demo c2/cart-and-windmills.html. From Section 3.2.
• glut/camera.c and the corresponding header file glut/camera.h for C, or jogl/Camera.java for JOGL, implement a “camera” API for use with OpenGL 1.1. This is a library for use in other programs, not itself a complete program. The corresponding API for JavaScript is part of my GLSim library, glsim/glsim.js. A camera is used in most of the following examples. Discussed in Section 3.3.
• glut/ifs-polyhedron-viewer.c and jogl/IFSPolyhedronViewer.java are C and Java versions of a program that lets the user view polyhedra that are defined as indexed face sets. The polyhedra models are defined in jogl/Polyhedron.java for Java and in glut/polyhedron.c and glut/polyhedron.h for C. This program also requires the camera API discussed in the previous item. From Section 3.4.
• glut/cubes-with-vertex-arrays.c, jogl/CubesWithVertexArrays.java, and the JavaScript version glsim/cubes-with-vertex-arrays.html demonstrate drawing using glDrawArrays and glDrawElements. From Section 3.4.
• glut/color-cube-of-spheres.c and jogl/ColorCubeOfSpheres.java draw a large number of spheres using a variety of rendering methods, and show the time that it takes to render the image. The point is to compare render times for different rendering methods, including display lists, glDrawArrays, and vertex buffer objects. The reader is not expected to understand all of the code in this program. From Section 3.4.
• glut/glut-starter.c, jogl/JoglStarter.java, and glsim/glsim-starter.html are “starter” files for writing OpenGL 1.1 applications using C, Java, and my JavaScript OpenGL simulator. These programs don’t draw anything, but they have function/method stubs for drawing as well as for mouse and keyboard interaction and animation. Discussed in Section 3.6.
• glut/four-lights.c and jogl/FourLights.java are an example of using light sources and material properties. The program demonstrates multiple, moving light sources and lets the user turn the lights on and off to see the effect. The demo glsim/four-lights-demo.html is a JavaScript version of the same program. From Section 4.2.
• glut/texture-demo.c is a C program that shows a variety of textures on a variety of objects. It depends on the files glut/textured-shapes.c and glut/textured-shapes.h, and on the folder glut/textures that contains the texture images used by the program. The Java version is jogl/TextureDemo.java, and it requires jogl/TexturedShapes.java, as well as the image folder jogl/textures. From Section 4.3.
• glut/texture-from-color-buffer.c and jogl/TextureFromColorBuffer.java demonstrate the technique of copying an image from the color buffer using the function glCopyTexImage2D(). Draws an animated 2D scene and then uses it as a texture on various objects. Requires the same textured shape libraries mentioned in the previous item. From Section 4.3.
• glut/texture-objects.c is a small program to demonstrate the use of texture objects to handle multiple textures. It is available for C only. From Section 4.3.

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