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diff --git a/doc/libgraphics.ms b/doc/libgraphics.ms index 2fada71..f25e270 100644 --- a/doc/libgraphics.ms +++ b/doc/libgraphics.ms @@ -1,22 +1,82 @@ +.\" Figure management +.nr FI 0 1 +.de FI +.ce +\fBFigure \\n+(FI\fR: \\$1 +.. + .TL libgraphics: Design and Implementation .DA .AU Rodrigo G. López rgl@antares-labs.eu -.SH -Introduction -.LP +.AB .I Libgraphics is a 3D computer graphics library that provides a way to set up a scene, fill it up with a bunch of models (with their own meshes and materials), lights and cameras, and start taking pictures at the user request. It implements a fully concurrent retained mode software renderer, with support for vertex and fragment/pixel shaders written -in C (not GPU ones, at least for now), a z-buffer, front- and +in C (not GPU ones, at least for now), and featuring a z-buffer, front- and back-face culling, textures and skyboxes, directional and punctual -lights, tangent-space normal mapping, ??? +lights, tangent-space normal mapping, among other things. +.AE .SH +Introduction +.LP +.QP +Write the intro last. +.NH +The scene +.PP +A scene is a container, represented as a graph, that hosts the +entities that make up the world. Each of these entities has a model +made out of a series of meshes, which in turn are made out of +geometric primitives (only +.I points , +.I lines +and +.I triangles +are supported). Each model also stores a list of materials. +.PP +.PS +.ps 7 +boxwid = 0.5 +boxht = 0.2 +linewid = 0.1 +lineht = 0.2 +box "Scene" +down; line from last box.s; right; line +box "Entity" +down; line from last box.s; right; line +box "Model" +down; line from last box.s; right; line +box dashed "Mesh" +down; line from last box.s; right; line +box "Primitive" +down +line from 2nd last line.s; line; right; line +box "Material" +reset +.ps 10 +.PE +.FI "The scene graph." +.NH 2 +Entities +.NH 2 +Models +.NH 2 +Meshes +.NH 2 +Primitives +.NH 2 +Materials +.NH +Cameras +.PP + +.NH The renderer .LP The @@ -31,33 +91,33 @@ themselves with shooting and “developing” a camera. It's implemented as a tree of concurrent processes connected by .CW Channel s—as seen in -.B "Figure 1" —, +.B "Figure 2" —, spawned with a call to .CW initgraphics , each representing a stage of the pipeline: -.IP +.IP • The .B renderer process, the root of the tree, waits on a .CW channel for a .CW Renderjob -sent by another user process, specifying a scene, a camera and a -shader table. It walks the scene and sends each +sent by another user process, specifying a framebuffer, a scene, a +camera and a shader table. It walks the scene and sends each .CW Entity individually to the entityproc. -.IP +.IP • The .B entityproc receives an entity and splits its geometry equitatively among the tilers, sending a batch for each of them to process. -.IP +.IP • Next, each .B tiler gets to work on their subset of the geometry (potentially in parallel)—see -.B "Figure 2" . +.B "Figure 3" . They walk the list of primitives, then for each of them apply the .B "vertex shader" @@ -67,24 +127,20 @@ project them into the viewport (screen space). Following this step, they build a bounding box, used to allocate each primitive into a rasterization bucket, or .B tile , -managed by one of the rasterizers; this is illustrated in -.B "Figure 3" . +managed by one of the rasterizers; as illustrated in +.B "Figure 4" . If it spans multiple tiles, it will be copied and sent to each of them. -.IP +.IP • Finally, the .B rasterizers receive the primitive in screen space, slice it to fit their tile, and -apply a rasterization routine based on its type (only -.I points , -.I lines -and -.I triangles -are supported). For each of the pixels, a +apply a rasterization routine based on its type. For each of the pixels, a .B "depth test" is performed, discarding fragments that are further away. Then a .B "fragment shader" is applied and the result written to the framebuffer after blending. +.PP .PS .ps 7 circlerad = 0.3 @@ -131,13 +187,7 @@ arrow from Tiler.T1 to Raster.Rd chop arrow from Tiler.T1 to Raster.Rn chop .ps 10 .PE -.B "Figure 1" : -The rendering graph for a -.B 2n -processor machine. -.SH -Tile-based rendering -.PP +.FI "The rendering graph for a \fB2n\fR processor machine." .PS .ps 7 Tiles: [ @@ -150,7 +200,7 @@ Tiles: [ Tn: box dashed "tile n" ] box ht last [].ht+0.1 wid last [].wid+0.1 at last [] -"Screen" rjust with .se at last [].nw - (0.1,0) +"Framebuf" rjust with .se at last [].nw - (0.1,0) Raster: [ moveht = 0.1 down @@ -168,8 +218,7 @@ line from Tiles.Td.e to Raster.Rd.w line from Tiles.Tn.e to Raster.Rn.w .ps 10 .PE -.B "Figure 2" : -Per tile rasterizers. +.FI "Per tile rasterizers." .PS .ps 7 Tiles: [ @@ -185,7 +234,7 @@ line from last [].w + (0.1,-0.05) to last [].n - (-0.1,0.25) line to last [].se - (0.3,-0.1) line to 1st line box ht last [].ht+0.1 wid last [].wid+0.1 at last [] -"Screen" rjust with .se at last [].nw - (0.1,0) +"Framebuf" rjust with .se at last [].nw - (0.1,0) Raster: [ moveht = 0.1 down @@ -202,32 +251,8 @@ arrow from Tiles.Td.e to Raster.Rd.w arrow from Tiles.Tn.e to Raster.Rn.w .ps 10 .PE -.B "Figure 3" : -Raster task scheduling. -.SH -The scene -.PP -.PS -.ps 7 -boxwid = 0.5 -boxht = 0.2 -linewid = 0.1 -lineht = 0.2 -box "Scene" -down; line from last box.s; right; line -box "Entity" -down; line from last box.s; right; line -box "Model" -down; line from last box.s; right; line -box "Mesh" -down; line from last box.s; right; line -box "Primitive" -down -line from 2nd last line.s; line; right; line -box "Material" -.ps 10 -.PE -.SH +.FI "Raster task scheduling." +.NH Frames of reference .PP Frames are right-handed throughout every stage. @@ -235,31 +260,46 @@ Frames are right-handed throughout every stage. .ps 7 RFrame: [ pi = 3.1415926535 + deg = pi/180 circle fill rad 0.01 at (0,0) "p" at last circle.c - (0.1,0) - xa = -5*pi/180 + xa = -5*deg arrow from (0,0) to (cos(xa),sin(xa)) "bx" at last arrow.end + (0.1,0) arrow from (0,0) to (0,1) "by" at last arrow.end - (0.1,0) - za = -150*pi/180 + za = -150*deg arrow from (0,0) to (cos(za)+0.1,sin(za)+0.1) "bz" at last arrow.end - (0.1,0) ] .ps 10 .PE -.B "Figure 4" : -Example right-handed rframe. -.SH +.FI "Example right-handed rframe." +.NH Viewports .PP +A +.I viewport +is a sort of virtual framebuffer, a device that lets users configure +the way they visualize a framebuffer, which changes the resulting +.I image (6) +after a call to its +.CW draw +or +.CW memdraw +methods. As of now, the only feature available is upscaling, which +includes user-defined filters for specific ratios, such as the family +of pixel art filters +.I Scale[234]x , +used for 2x2, 3x3 and 4x4 scaling +.I [?] . respectively .PS .ps 7 View: [ boxwid = 3 boxht = 2 box with .nw at (-1,1) - "framebuffer" at last box.s + (0,0.2) + "Framebuf" at last box.s + (0,0.2) circle fill rad 0.01 at (-1,1) "p" at last circle.c - (0.1,0) arrow from (-1,1) to (-1,1) + (1,0) @@ -269,5 +309,9 @@ View: [ ] .ps 10 .PE -.B "Figure 5" : -Illustration of a 3:2 viewport. +.FI "Illustration of a 3:2 viewport." +.SH +References +.PP +.IP [?] +https://www.scale2x.it/ |