rtrace - ray tracing program Antonio Costa, INESC-Norte, 1989 1994 command performs ray tracing from a text file which must describe a scene with objects, lights, surface definitions, textures, etc. This scene file must be in the appropriate format, as described bellow. Basically, ray tracing is an algorithm for the creation of realistic images from the geometry and attributes of objects, lights, etc. This ray tracer supports several types of objects (sphere, box, bicubic patch, cone, cylinder, polygon, triangle and text), CSG and list operations, different light types, reasonable surface definitions, lots of textures, several anti- aliasing schemes, depth of field, stereoscopic image creation and so on... [wimage-width] [himage-height] The parameters and define the image size. Defaults are 256x256. [Aaliasing-threshold] [Sshading-threshold] [Tambient-threshold] The parameters (pixel supersampling), (shading rays propagation) and (ambient rays distribution caching) control the image quality (0-best, 1-poor). Defaults are 0.05, 0.01 and 0 (no ambient threshold). Good ranges are 0.1-0.03, 0.01-0.001 and 0.01- 0.00001, respectively. If the parameter is negative, contrast between pixel colors will be used instead of difference. [aantialiasing-mode] The parameter chooses adaptive supersampling antialiasing (0- default), semi-adaptive supersampling antialiasing (1) or normal supersampling antialiasing (2-should be used with nonzero focal apertures). [Bmaskfile] The parameter creates a file with a background mask, suitable for mixing images (it is like an alpha channel). [bbackface-mode] The parameter controls the removal of backface polygons and triangles from the scene. Default is no removal (0). Partial removal (1) is made when finding candidates for ray-object intersection; if there are any objects facing against the ray, they will be skipped. Full removal (2) is made during the read of the scene; if there are any objects facing against the viewer, they are thrown away completely (this may cause incorrect lighting and shadowing). [ccluster-size] The parameter controls the enclosing of objects (number of grouped objects per cluster) in the object hierarchy. Use a low value for sparse scenes, a high value for dense scenes (4- default). Negative values means to use a method similar to the one of Goldsmith/Salmon for clustering objects (0 uses the default value for this method). Most of the times it performs better than the default method. [dambient-levels] The parameter defines the number of shading levels (shading tree depth) in which ambient lighting calculations will be done through ray distribution (0-default, ie, no ray distribution). Use low values! [Dambient-samples] The parameter defines the maximum number of distributed rays to be used in ambient lighting calculations (16-default). Again, use with care. [iintersect-mode] The parameter chooses, in adaptive supersampling antialiasing, between testing all scene objects (1) or only the objects found at the pixel corners and inside (0-default; this greatly reduces CPU time, but with very small objects, it sometimes fails). [Iintersect-adjust-mode] The parameter avoids some problems with invalid self- intersections (1) (0-default). Scenes with text objects should be traced with this parameter equal to 1. [jjittering-mode] The parameter chooses jittered sampling (1) or not (0-default). Sometimes, activating it produces better images from scenes with small tricky details. [llighting-mode] The parameter controls the generation of shadow rays through non-opaque objects: 0-none (default), 1-partial, 2-full. If a scene has translucent objects, to obtain realism one should use 1 or 2 (better). [mshading-mode] The parameter chooses between shading models: 0-normal phong, 1- strauss (default but slower) (note: this model was developed by Paul Strauss of SGI). [nnormal-mode] The parameter controls the correction of surface normals, so that it points against the incident ray: 0-always (default), 1-only inside objects. With "correct" objects, it is good to use 1. [xwalk-mode] The parameter controls how pixels are scanned inside the picture. Default is 0, which is a serpertine walk (left to right, right to left, and so on). 1 means an Hilbert (fractal) walk, which demands more memory, but maximizes the effect of pixel coherency (in scenes with many objects, it can save some time!). Perhaps 1 should be the default... [znormal-check-mode] The parameter controls the correction of surface normals when textures that modify the normal are used, as they may sometimes create strange surface effects. This tends to happen if the scale of the normal perturbation is big. 0-no correction (default), 1-correction. [Rrawfile] The parameter creates a raw image file, without any antialiasing (all defects show up!). [psampling-levels] The parameter controls the amount of sampling levels inside pixels: 0-none (default) ... 3-maximum. A reasonable value is 2 for high resolutions, but for small ones 3 gives better (and slower) results. [sshading-levels] The parameter establishes a maximum shading tree depth (default is 8). When a scene has transparent/reflective objects, it may be important to lower this parameter, or else the tracing never stops. In the other cases, there should be no problem allowing it to be big. [ttexture-mode] The parameter allows the definition of texture(s) for the objects: 0-no textures (default), 1-with textures defined inside objects field, 2-with textures defined after objects field. As textures may consume much CPU time, they should be activated only for final images. [vview-mode] The parameter chooses the view mode: 0-normal (default), 1-left eye, 2-right eye. [Pfocal-aperture] The parameter defines the focal aperture of the camera (default 0.0, ie, pinhole camera). If different than zero, there is depth of field, and so adaptive supersampling antialiasing will not work well. [Ffocal-distance] The parameter defines the focal distance of the camera (default is the distance from the eye point to the look point). [Estereo-separation] The parameter controls the separation between the left and the right eye. If negative, it represents a percentage of the gaze distance. [Ooutput-format] The parameter chooses between the PIC format (0-default) or the PPM format (1). [Vverbose-mode] The parameter supresses any messages (0) or shows listing of parameters (1), previous plus statistics (2-default) or previous plus a line by line echo of the tracing (3-default on DOS and transputers). Note: when running the DOS DJGPP version, there are two extra values that display the picture on the screen, -1 for grayscale or -2 for color. These values supress any messages. [+Oobjects-max] The parameter defines the maximum number of objects to use (default is 25000). [+Llights-max] The parameter defines the maximum number of lights to use (default is 16). [+Ssurfaces-max] The parameter defines the maximum number of surfaces to use (default is 256). [+Ccsg-level-max] The parameter defines the maximum number of levels in CSG trees to use (default is 256). [Meeye-file] The parameter is the name of a file that contains positions for movie fly-throughs (3 real numbers representing XYZ in each line). In mode, the scene is read only once and successive images are produced and stored in the picture file. [Mllook-file] The parameter is the name of a file that contains positions for movie fly-throughs. [Muup-file] The parameter is the name of a file that contains vectors for movie fly-throughs. [Maangle-file] The parameter is the name of a file that contains apertures for movie fly-throughs (2 real numbers in each line). [M+movie-frames-max] The parameter defines the maximum number of frames to produce (default is 50). The data internal syntax (SFF) is described bellow. The file will contain the ray traced image. The image file has a 4 byte header composed of LS and MS bytes, LS and MS bytes and RGB byte triplets starting in the upper left corner line by line to the lower right corner. The straightforward use: rtrace demo.sff demo.pic is not recommended, as ray tracing usually takes lots of CPU time to execute. So, it is better to do: rtrace demo.sff demo.pic >demo.log & or then use nice (1) or similar strategies. No bugs known. They have to be hidden deep somewhere, as usual. SFF (Simple File Format) description follows. This is a very crude ASCII format, almost like if generated by a lexical analyser. The idea is to have other programs create scene descriptions in more sophisticated ways, and then feed the tokenized results to this program. So, it behaves accordingly to the UNIX philosophy: one program for one task. Complaints are not wellcome!... There is a reasonable scene language available (SCN) that allows the creation of scenes with much more flexibility; the converter is called 'scn2sff' and works directly with this program. Note: the ^(circunflex) character represents start of line. [Start ofFile] ^... Comment ^Eye(X Y Z) ^Look(X Y Z) ^Up(X Y Z) ^View_angle(H V) [1,89 degrees] ^... Comment ^Background(R G B) ^Ambient(R G B) ^... Comment ^Light_type(Type) Position(X Y Z) Bright(R G B) ... | | | /---------------------------/ | | V V 1-POINT: 2-DIRECTIONAL: Direction(X Y Z) Angle(La) Light_Factor(Lf) 3-EXTENDED: Radius(R) Samples(N) 4-PLANAR: Vector1(X Y Z) Vector2(X Y Z) Samples1(N) Samples2(N) ^Etc ^ ^... Comment ^Surface_type(Type) Color(R G B) ... | | | /----------------------/ | | V V 1-: Dif(R G B) Spec(R G B) Phong(Pf) Metal(Mf) Trans(R G B) 2-: Smoothness(R G B) Metalness(R G B) Transmission(R G B) ^Etc ^ ^... Comment ^Object_type(Type) Surface_ID(S) Refraction(Re) ... | | | /------------------------/ | | V V 1-SPHERE: Center(X Y Z) Radius(R) 2-PARALLELIPIPED: Center(X Y Z) Size(X Y Z) 3-PATCH: Origin(X Y Z) Scale(X Y Z) Filename(...) 4-CONE/CYLINDER: Base(X Y Z) Base_Radius(Rb) Apex(X Y Z) Apex_Radius(Ra) 5-POLYGON: Origin(X Y Z) Scale(X Y Z) Filename(...) 6-TRIANGLE: Origin(X Y Z) Scale(X Y Z) Filename(...) 7-TEXT: Filename(...) or 64-TEXTURE: see below 65-TRANSFORMATION: Object_ID(I) Transform(X1 Y1 Z1 W1 ... X4 Y4 Z4 W4) 66-CSG 0: Surface_ID(S) Refraction(Re) (Union-0 Sub-1 Int-2) CSG 1: Next CSG member CSG 2: End of CSG 67-LIST 0: Surface_ID(S) Refraction(Re) LIST 1: End of List ^Etc ^ ^... Comment ^Texture_type(Type) Object_ID(I) | Transform(X1 Y1 Z1 W1 ... X4 Y4 Z4 W4) | ... | | V V 0-NULL: 1-CHECKER: Surface_ID(S) 2-BLOTCH: Scale(K) Surface_ID(S) [Filename(...) or -] 3-BUMP: Scale(K) 4-MARBLE: [Filename(...) or -] 5-FBM: Offset(K) Scale(K) Omega(K) Lambda(L) Threshold(K) Octaves(O) [Filename(...) or -] 6-FBMBUMP: Offset(K) Scale(K) Lambda(L) Octaves(O) 7-WOOD: Color(R G B) 8-ROUND: Scale(K) 9-BOZO: Turbulence(K) [Filename(...) or -] 10-RIPPLES: Frequency(K) Phase(K) Scale(K) 11-WAVES: Frequency(K) Phase(K) Scale(K) 12-SPOTTED: [Filename(...) or -] 13-DENTS: Scale(K) 14-AGATE: [Filename(...) or -] 15-WRINKLES: Scale(K) 16-GRANITE: [Filename(...) or -] 17-GRADIENT: Turbulence(K) Direction(X Y Z) [Filename(...) or -] 18-IMAGEMAP: Turbulence(K) Mode(K) Axis(X Y) Filename(...) 19-GLOSS: Scale(K) 20-BUMP3: Scale(K) Size(K) ^ ^... Comments [End of File] 1. Valid ranges of data RGB must be in [0,1[ (Note: RGB brightness of lights may be between ]-300,300[; negative values mean to not attenuate with distance). XYZ must be in [- 10000,10000] Factor must be in [0,300[ Filename must a valid filename for the operating system, or then '-', in which case data is read from the standard input or the current SFF stream. 2. Patch specification File format for PATCH (bicubic 4-sided patch): [Start] ^Patch_1_Index(1 2 3 4 5 6 7 8 9 10 11 12) ^Patch_2 ^Etc ^ ^Patch_Index_1_Coords(X Y Z) ^Patch_Index_2_Coords(X Y Z) ^Etc ^ ^... [End] 3. Polygon specification File format for POLYGON (n-sided planar polygon): [Start] ^Polygon_1_Vertex_Number Polygon_1_Index(1 2 3 ...) ^Polygon_2 ^Etc ^ ^Polygon_Index_1_Coords(X Y Z) ^Polygon_Index_2_Coords(X Y Z) ^Etc ^ ^... [End] 4. Triangle specification File format for TRIANGLE (3-sided polygon with vertex normals): [Start] ^Triangle_1_Vertice_1(X Y Z) Normal_1(X Y Z) Vertice_2(X Y Z) Normal_2(X Y Z) Vertice_3(X Y Z) Normal_3(X Y Z) ^Triangle_2 ^ ^... [End] If the surface is has index 0, then you must specify 3 surface indices after all the vertices and normals. 5. An example [Start of File] View 25 25 7 - Eye point 0 0 0 - Look point 0 1 0 - Up vector 30 30 - View angles Colors 0.196 0.6 0.8 - Background (Sky Blue) 0.1 0.1 0.1 - Ambient light Lights 1 0 60 60 0.9 0.9 0.9 - Point Light 1 1 20 40 -7 0.9 0.9 0.9 - Point Light 2 Surfaces 1 0.6 0.8 0.196 0.99 0.99 0.99 0 0 0 0 0 0 0 0 1 0.9 0.9 0.9 0.5 0.5 0.5 0.5 0.5 0.5 50 1 0 0 0 1 0.5 0.5 0.5 0.1 0.1 0.1 0.1 0.1 0.1 200 0.7 0.8 0.8 0.8 1 0.9 0.2 0.2 0.99 0.99 0.99 0 0 0 0 0 0 0 0 Objects 5 1 1.0 0 0 0 15 15 15 - Polygon 4 1 2 3 4 1 0 1 1 0 -1 -1 0 -1 -1 0 1 2 2 1.0 0 2 0 7 2 3 - Parallelepiped 2 3 1.5 0 5 10 3 5 3 - Parallelepiped 1 4 1.0 7 15 -7 3 - Sphere Textures 2 1 2 0 0 0 0 2 0 0 0 0 2 0 0 0 0 1 0.4 4 4 2 5 0 0 0 0 5 0 0 0 0 5 0 0 0 0 1 5 4 10 0 0 0 1 10 0 0 1 1 10 0 0 0 0 1 0 0.6 0.5 2 0.1 6 Demo / 11-OCT-1989 / Antonio Costa [End of File] To ray trace without textures, do: rtrace demo.sff demo.pic >&demo.log else, do: rtrace t2 demo.sff demo.pic >&demo.log Another example with INESC symbol: [Start of File] View 45.0 45.0 81.0 - Eye point 45.0 45.0 -81.0 - Look point 0.0 1.0 0.0 - Up vector 30 30 - View angles Colors 0.196 0.6 0.8 - Background (Sky Blue) 0.3 0.3 0.3 - Ambient Lights 1 0.0 100.0 100.0 1 1 1 - Light 1 (White) 1 90.0 100.0 100.0 1 1 0 - Light 2 (Yellow) Surfaces 1 0.557 0.420 0.137 0.8 0.7 0.7 0.2 0.3 0.3 30 0.8 0 0 0 1 0.137 0.420 0.557 0.5 0.5 0.6 0.5 0.5 0.4 5 0.2 0 0 0 1 0.600 0.800 0.200 0.9 0.9 0.9 0.0 0.0 0.0 1 0 0 0 0 Objects 1 1 1.0 10.0 09.5 0.0 4.5 - Sphere 1 1 1.0 10.0 26.5 0.0 4.5 1 1 1.0 20.0 63.5 0.0 4.5 1 1 1.0 20.0 80.0 0.0 4.5 1 1 1.0 40.0 09.5 0.0 4.5 1 1 1.0 40.0 26.5 0.0 4.5 1 1 1.0 40.0 43.5 0.0 4.5 1 1 1.0 50.0 80.0 0.0 4.5 1 1 1.0 60.0 53.0 0.0 4.5 1 1 1.0 70.0 09.5 0.0 4.5 1 1 1.0 70.0 43.5 0.0 4.5 4 2 1.0 10.0 30.0 0.0 1.5 10.0 70.0 0.0 1.5 - Cylinder 1 2 1.0 10.0 70.0 0.0 1.5 4 2 1.0 10.0 70.0 0.0 1.5 17.5 77.5 0.0 1.5 4 2 1.0 12.5 12.0 0.0 1.5 20.0 19.5 0.0 1.5 1 2 1.0 20.0 19.5 0.0 1.5 4 2 1.0 20.0 19.5 0.0 1.5 20.0 60.0 0.0 1.5 4 2 1.0 22.5 61.0 0.0 1.5 37.5 46.0 0.0 1.5 4 2 1.0 37.5 12.0 0.0 1.5 30.0 19.5 0.0 1.5 1 2 1.0 30.0 19.5 0.0 1.5 4 2 1.0 30.0 19.5 0.0 1.5 30.0 33.5 0.0 1.5 1 2 1.0 30.0 33.5 0.0 1.5 4 2 1.0 30.0 33.5 0.0 1.5 37.5 41.0 0.0 1.5 4 2 1.0 30.0 26.5 0.0 1.5 36.5 26.5 0.0 1.5 4 2 1.0 40.0 47.0 0.0 1.5 40.0 70.0 0.0 1.5 1 2 1.0 40.0 70.0 0.0 1.5 4 2 1.0 40.0 70.0 0.0 1.5 47.5 77.5 0.0 1.5 4 2 1.0 42.5 12.0 0.0 1.5 50.0 19.5 0.0 1.5 1 2 1.0 50.0 19.5 0.0 1.5 4 2 1.0 50.0 19.5 0.0 1.5 50.0 43.0 0.0 1.5 1 2 1.0 50.0 43.0 0.0 1.5 4 2 1.0 50.0 43.0 0.0 1.5 57.5 50.5 0.0 1.5 4 2 1.0 67.5 12.0 0.0 1.5 60.0 19.5 0.0 1.5 1 2 1.0 60.0 19.5 0.0 1.5 4 2 1.0 60.0 19.5 0.0 1.5 60.0 33.5 0.0 1.5 1 2 1.0 60.0 33.5 0.0 1.5 4 2 1.0 60.0 33.5 0.0 1.5 67.5 41.0 0.0 1.5 5 3 1.0 0.0 4.0 0.0 200.0 200.0 200.0 - Polygon 4 1 2 3 4 1.0 0.0 1.0 1.0 0.0 -1.0 -1.0 0.0 -1.0 -1.0 0.0 1.0 End INESC Logo / 23-FEB-1989 / Antonio Costa Copyright (C) 1988, 1994 Antonio Costa. Permission is granted to use this file in whole or in part for any purpose, educational, recreational or commercial, provided that this copyright notice is retained unchanged. This software is available to all free of charge by anonymous FTP. 08-Nov-94 Antonio Costa Release 8.4.2 acc@asterix.inescn.pt