Line Drawing Algorithm For GPU Base On NPR

Non-Photorealistic-Rendering is one of the most important branches of Graphics. Afterdevelopment more than a decade, it has become the key technology in industry. Nowadays,the research for NPR is focused on Application, and become more specific. For any NPRsystem, it has a base step, which is called lines exaction, because lines are the raw materialsfor NPR system. The problem all NPR system facing is that we cannot get speed and accuracyat the same time. Especially for some applications which need accuracy, we have to give upspeed.This page is focused on two kinds of lines, suggestive contour and silhouette. Silhouetteis used for drawing outline while the suggestive contour is good at expressing inner featuresof the model.This page has implemented line exaction first of all, because line is the base element forNPR system. I use TriMesh to read the ply file and calculate the normal、curvature、derivate ofcurvature. And then go through the faces to find the lines I want according to the formula.After exacting the lines, I draw the lines as strokes. Extending the points in their normaldirection, I get some quadrilaterals. And then, I use texture to put color on the quadrilateralsand get the stroke effect.Taking into account that the algorithm for extracting lines has natural parallelism and thepowerful GPU, implementing the algorithm on GPU can improve the efficiency of the systemat once. This page will show you how to divide the NPR system in two parts, preprocessingpart and dynamic calculation part. I preprocess some data using CPU, and then calculate therest in GPU dynamically.