GM(Graphics Masters) CSE 이동형 CSE 최태준 CSE 신재훈

 A type of NPR(Non-photorealistic rendering )  Describes object using parallel or cross lines  Contour, tone, and curvature are represented by those lines.  Density of lines and their overlaps are major factors to consider in implementing hatching.

 Picture from Wikipedia

 OpenGL  Visual Studio 2005  C++  Other Resources  OBJ files  Jpeg decoder : CxImage Library  GTS Library(GNU Triangulated Surface Library)  Tone Texture : RenderMonkey SDK  OBJ2GTS : Selfmade App For Converting

 Major Issues  Contour  Tone  Curvature  Our Own Features  Speed Lines  Animation Tests

 Contour shaking  Multiple Contour drawing  Picture from “Real-Time Pencil Rendering”

 Detection Contour 1. Select two faces 2. Check angle between two faces using Normal Vector 3. If angle < 150 then If two faces share same edge then Assign Contour - Additional Check Routine : Suggestive contours for conveying shape  Draw Contour 1. Draw additional two lines 2. Edge’s Vertex(x,y,z) => Line’s Vertex(x+r, y+r, z+r) 3. r = ~

 Discrete multiple level of tones  Mipmap for scaling  Interpolation at each vertex  Picture from “Real-Time Hatching”

Weight : 0 Weigh : 1 Weight : 2 Weight : 3 Weigh : 4 Weight : 5

For each Face For each Vertex 1) v = Normalize(VertexCoord – LightCoord) 2) n = VertexNormalVector 3) result = (v.DotProduct(n) + 1.0f) * 3.0f 4) weighting(result) Weight => 0.0 ~ 6.0 5) Blend Texture Image - MultiTexture If weight is 3.4 => weight 3 : 60%, weight 4 : 40% If weight is 5.5 => weight 5 : 50%, weight 5 : 50%

 Rotate textures for voluminousness  3-way Blending Each Vertex Per Face - Compute principal direction  Use GNU Triangulated Surface Library( * From “Real-Time Pencil Rendering” paper

For each Face For each Vertex 1) Get Principal Directions of Vertex 2) angle = arctan(y / x) x : x of principal directions y : y of principal directions 3) Rotate texture by angle 4) Texture Mapping

 To express speed effectively in hatching, we used extra lines.  The faster object moves, the longer lines are drawn.  Speed line is expressed with gradation to express gradual speed change

 Flag animation is rendered to show that hatching can well render dynamic scenes.  Flag is set by basic rectangular lattice.  Flag animation is done as z value changes along sin function.  Like water animation.

 Any questions?