Procedural Books
Why Procedural Books?
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The topic of books in our Dragon’s cave came up just before the beginning of the Fall semester of production. The group needed to create multiple variations of books that came in all shapes and sizes. Modeling would take time and would seem to be extremely repetitive throughout the entire process. I looked into the possibility of creating a procedural book in Houdini that would allow all aspects of the book to be altered with a few clicks of the mouse.
While creating a workflow for a procedural book, I aimed to create a controller that would allow the width, height, spine curve, bend crease, cover thickness, page count, and surface breakup to all be changed easily. I came up with the ability to link all changes the tunable parameters in one node acting as a controller for the entire procedural model. Each parameter was linked to a slider, a float or an integer.
Having a controller node would allow for the settings to be altered to create a new book variation in seconds rather than the painful process of going through multiple nodes altering settings to find a desirable product. The control node can be seen in the first screenshot. A high poly and low poly version can be made in two clicks.
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Procedure to Create the Book
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The book is built upon multiple lines combined together. A book is symmetrical and can mirrored vertically for efficiency. The lines to create the structure of the book are one for the spine, one for the crease, one for the cover width, one for the cover height, one for number of pages, one for page width, and one for page height. The cover width line is connected to the crease line and the crease line is connected to the spine line. Now that the half of the book has been guided, I can now mirror the lines before extruding. Mirroring before extrusion allows for less complication and clean topology. These three lines are the foundation lines of the books structure that are then extruded based on the cover height line’s value. The cover is once again extruded to give the cover its thickness that all books have. No book covers are just a sheet of paper, not even paperbacks.
The pages of the book are a separate structure for the model. A line is aligned between the top and bottom cover measuring the distance between the two. Having the distance between the top and bottom covers, I can resample the line to dictate the number of pages a book will have. The distance line is then aligned to the curvature of the full spine so that the width line guiding the pages can be attached to this line. The lines, width and height, of the pages extend to the edge of the cover and are then clipped inwards to allow the cover to fully protect the pages from damage.
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Now that both the cover and pages have been created I move on to creating some surface breakup because the books in the Dragon cave are aged by time and their environment and not considered to be in new condition. The second layer of noise is added to the pages to give the edges some warping and inconsistency. In a cave moisture can warp the pages and aging can create more inconsistency in page shape over time.
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Modeling Finished, Now What?
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The book has been completely guided and modeled. UVs can be simply generated an auto UV tool Houdini has in its game development tools. I select the preferred edges for UV shells and the tool automatically generates the UVs.
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The book in whatever variation it can exist is now ready for export. A null node can be placed at the end of the graph where the model can be exported as an .obj to be imported into Maya at a later date.
