Description

CS4247
Graphics Rendering Techniques
Assignment 4
Progressive Refinement Radiosity
Dates
Assignment Overview
 You are provided with an incomplete C/C++ program that implements the progressive refinement radiosity algorithm
 Task 1
 Complete the program
 Generate a radiosity solution for the sample input scene
 Task 2
 Create a new input scene model
 Generate a radiosity solution for the new scene
Learning Objectives
 Implementing the Progressive Refinement Radiosity Algorithm
 After completing the assignment, you should have learned
How to use the Hemicube algorithm to estimate form factors:
 How to compute delta form factor for each pixel on the hemicube How to set up OpenGL views to project the scene onto the faces of the hemicube
 How to use the item buffering technique to identify the patch that occupies a pixel
How the progressive refinement radiosity algorithm works:
 How to “shoot” light power from a shooter patch to the gatherer patches, and update the radiosity values of these patches
 How to update the unshot power of a shooter patch with the new power received by its child gatherer patches
 How to terminate the progressive refinement radiosity computation
What Are Provided (1) – For Windows
 Download the file cs4247_2021S2_assign4_todo_(win-vs2017).zip from the Assignments folder in LumiNUS Files The ZIP file contains a Visual Studio 2017 solution file assign4.sln. The solution has three C/C++ projects
 QuadsViewer
 RadiositySolver
 RadiosityViewer
 Tip: In Visual Studio, to make a project the default project to be built and run, you can right-click on the project name in the Solution
Explorer, and select “Set as StartUp Project”
What Are Provided (1) – For macOS
 Download the file cs4247_2021S2_assign4_todo_(mac-xcode).zip from the Assignments folder in LumiNUS Files
 The ZIP file contains the Xcode project assign4.xcodeproj, which has the following three C/C++ targets
 QuadsViewer
 RadiositySolver
 RadiosityViewer
What Are Provided (2)
 QuadsViewer is a completed (old-style) OpenGL application that lets you preview the input scene model and check the subdivision of the input quads into smaller “shooter” quads and even-smaller “gatherer” quads
 The default input scene model file is model.in
 Gatherer quads are obtained by subdividing shooter quads Press “m” to cycle through display of the input quads, the shooter quads, and the gatherer quads
 In quadsviewer.cpp, the size of the shooter and gatherer quads are controlled by the values of maxShooterQuadEdgeLength and maxGathererQuadEdgeLength respectively
 These two values are from the input scene model file model.in
 radiositysolver.cpp also uses these two values for the same purpose
What Are Provided (3)
 RadiositySolver is the incomplete program that
 Reads the input scene model from model.in
 Subdivides the input quads into “shooter” and “gatherer” quads
 In radiositysolver.cpp, the size of the shooter and gatherer quads are controlled by the values of maxShooterQuadEdgeLength and maxGathererQuadEdgeLength respectively
These two values are from the input scene model file model.in Computes a radiosity solution for the scene
 This step is the part to be completed
 Computes vertex radiosities from the patch radiosities
This step can take very long to run, so you should first test your radiosity algorithm implementation with a model with not too many gatherer quads
 Outputs the model with radiosity solution to the file model.out
What Are Provided (4)
 RadiosityViewer is a completed (old-style) OpenGL application that lets you view the model output by RadiositySolver
 Reads in a model with radiosity solution from file model.out
 Performs simple tonemapping to map radiosity values to displayable color values (i.e. to R, G, B values from 0.0 to 1.0)
 Renders the polygons using the tonemapped radiosity values as vertex colors
 You can try the viewer on the given sample model file cornell_box.out
 First, copy cornell_box.out to the file model.out
 Note that the sample cornell_box.out has been “watermarked” with some bright and dark patches — your radiosity solution for cornell_box.in should not have those
Task 1
Complete only the source file radiositysolver.cpp, which is part of the RadiositySolver project
 Complete the code at places marked “WRITE YOUR CODE HERE”
 You can add additional functions to the file Use good coding style and document your code adequately (otherwise marks deducted)
 Study the files quadmodel.{h,cpp} to see how the scene model and its subdivided quads are represented
 You can make use of helper functions found in common.h and vector3.h
Task 1 (continue)
 Test your program on the provided sample input scene model cornell_box.in
 Before running your RadiositySolver, copy cornell_box.in to the file model.in
 After running your RadiositySolver, copy the output file model.out to cornell_box_my.out
 View your radiosity solution model.out using RadiosityViewer
(in non-wireframe mode) and capture three different snapshots
 On Windows 10, you can use the Snip & Sketch tool (press Win + Shift + “S”) to take a snapshot of the window and save the image
 Use the default window size
 Save the three snapshots to image files
cornell_box_1.png cornell_box_2.png
cornell_box_3.png
Task 1 — RadiositySolver Explained
 RadiositySolver uses to the Progressive Refinement Radiosity algorithm to compute patch radiosity of each gatherer quad
Pre-compute the delta form factors on the top face (already done) and side faces of the hemicube
 Note that top hemicube face has same pixel resolution as the default window size (always a square)
Progressive Refinement Radiosity loop
 Find the shooter quad with the greatest unshot power
 Use a hemicube to compute form factors from the shooter quad to each of the gatherer quads
 Update the radiosity of each of the gatherer quads
 Update the unshot power of each shooter patch with the new power received by its child gatherer patches
 Terminate loop if max iterations is reached
Task 2
 Create a new scene model
 Study the sample scene model cornell_box.in to find out the input model file format
 Name your new scene new_model.in
 Run your RadiositySolver program on new_model.in to output new_model.out
 View new_model.out in RadiosityViewer and capture three different snapshots
 Use the default window size
 Save your snapshots to image files
new_model_1.png new_model_2.png
new_model_3.png
What to Submit
 Only the following 10 files
Task 1
 radiositysolver.cpp
 cornell_box_my.out
 cornell_box_1.png, cornell_box_2.png, cornell_box_3.png Task 2
 new_model.in
 new_model.out
 new_model_1.png, new_model_2.png, new_model_3.png
How to Submit
 Put only the required files in a single ZIP file
 Name your ZIP file your-student-number_assign4.zip
 e.g. A0123456X_assign4.zip
 Submit your ZIP file to the Assignment 4 Submission folder in LumiNUS Files
 Please delete your older versions
Other Requirements
 Programming languages and APIs
 C / C++
 OpenGL 1.1 (old-style OpenGL; no shader)
 GLU & GLUT / FreeGLUT
 No other third-party APIs are allowed
 Platform
 You can develop your program on any OS and IDE However, the final submitted version must be compilable/buildable in Microsoft Visual Studio 2017
Grading
 Maximum marks is 100
 Constitutes 9% of total marks for CS4247
 Marks allocation
 Task 1 – 80 marks
 Correctness & Coding Style
 Task 2 – 20 marks
 Task completion (10 marks)
 Aesthetics and complexity (10 marks)

The End