Graphics Pipeline Bringing it all together

Implementation The goal of computer graphics is to take the data out of computer memory and put it up on the display in a suitable manner –Charts –Graphs –Still images –Video –Real-time animation

Implementation The method of implementation is the Graphics Pipeline –A sequence of operations that perform stepwise transformations of the data Vertex Processor Clipper & Primitive Assembler RasterizerFragment Processor Vertex List Display

Vertex List This is the internal (memory) representation of the scene The list represents a set of objects by their vertices and other attributes (color, texture, material, etc.) It comes from –A scene graph created by a modeler –Data generated by a program –Wherever You’ve seen this in your programs –I gave you a number of model files

Vertex Processor Two primary functions: –Transform object coordinates from model coordinate system to the scene (camera) coordinate system –Set the object’s color Per object shading Per triangle (polygon) shading Per vertex shading Note that the actual shading may not be done until rasterization

Vertex Processor Triangles (polygons) transformed from model coordinates Per Triangle shading Surface normals Per Vertex shading

Clipper & Primitive Assembler Removal of objects that are out of the field of view –Things that can’t be seen by the “camera” –Some objects are only partially out of the scene and therefore must have their primitives (triangles, polygons) truncated at viewing boundaries

Clipper & Primitive Assembler The view frustum

Rasterizer Convert the object primitives (triangles, polygons) to pixels suitable for placement on the display –Scan conversion of lines – Bresenham –Scan conversion of curves – Hermite/Bezier –Scan conversion of triangles (Gouraud, Phong shading) Utilizes the frame buffer (we used a Java BufferedImage object)

Fragment Processor Place the rasterized pixels in the frame buffer –Alpha blending for opaque/transparent objects –Hidden surface removal for object occlusion (by self and other objects) –Texture mapping (attach pictures to objects) –Bump mapping (rough up the surface of an object by manipulating its surface normals Note that this updates the pixels previously placed in the frame buffer

Fragment Processor Texture mapping Bump mapping

Technology The graphics pipeline is implemented in software or in hardware via a graphics processing unit (GPU) nVidia GeForce 6