Visualizing Data Flows in Computer Graphics Programs for Code Comprehension and Debugging

Abstract

OpenGL is the most widely used API and programming language in college-level computer graphics courses. However, OpenGL programs are difficult to comprehend and debug because they involve programming for both CPU and GPU and the data transfer between them. Modern OpenGL is a complex data flow machine with multiple programmable stages, and it is difficult to trace the partially hidden data flows in the source code written in C++, OpenGL, and OpenGL Shading Language. We have developed a web-based data visualization tool to analyze OpenGL source code and generate interactive data flow diagrams from the source code. The diagrams can help novice programmers build clear mental images of complex data flows. The source code viewer and the data flow diagram are synchronized so that a user can select an OpenGL API call, and the corresponding component in the data flow diagram is highlighted, and vice versa. A programmer can visually step through the data flows and detect specific bugs that are otherwise difficult to find. The main contribution of this paper is an interactive learning tool for computer graphics education.