README_ALGORITHM.md
1SkQP Render Test Algorithm
2==========================
3
4The following is a description of the render test validation algorithm that
5will be used by the version of SkQP that will be released for Android Q-release.
6
7There is a global macro constant: `SK_SKQP_GLOBAL_ERROR_TOLERANCE`, which
8reflects the `gn` variable `skia_skqp_global_error_tolerance`. This is usually
9set to 8.
10
11First, look for a file named `skqp/rendertests.txt` in the
12`platform_tools/android/apps/skqp/src/main/assets` directory. The format of
13this file is: each line contains one render test name, followed by a comma,
14followed by an integer. The integer is the `passing_threshold` for that test.
15
16For each test, we have a `max_image` and a `min_image`. These are PNG-encoded
17images stored in SkQP's APK's asset directory (in the paths `gmkb/${TEST}/min.png`
18and `gmkb/${TEST}/max.png`).
19
20The test input is a rendered image. This will be produced by running one of
21the render tests against the either the `vk` (Vulkan) or `gles` (OpenGL ES)
22Skia backend.
23
24Here is psuedocode for the error calculation:
25
26 function calculate_pixel_error(pixel_value, pixel_max, pixel_min):
27 pixel_error = 0
28
29 for color_channel in { red, green, blue, alpha }:
30 value = get_color(pixel_value, color_channel)
31 v_max = get_color(pixel_max, color_channel)
32 v_min = get_color(pixel_min, color_channel)
33
34 if value > v_max:
35 channel_error = value - v_max
36 elif value < v_min:
37 channel_error = v_min - value
38 else:
39 channel_error = 0
40 pixel_error = max(pixel_error, channel_error)
41
42 return max(0, pixel_error - SK_SKQP_GLOBAL_ERROR_TOLERANCE);
43
44 function get_error(rendered_image, max_image, min_image):
45 assert(dimensions(rendered_image) == dimensions(max_image))
46 assert(dimensions(rendered_image) == dimensions(min_image))
47
48 max_error = 0
49 bad_pixels = 0
50 total_error = 0
51
52 error_image = allocate_bitmap(dimensions(rendered_image))
53
54 for xy in list_all_pixel_coordinates(rendered_image):
55 pixel_error = calculate_pixel_error(rendered_image(xy),
56 max_image(xy),
57 min_image(xy))
58 if pixel_error > 0:
59 for neighboring_xy in find_neighbors(xy):
60 if not inside(neighboring_xy, dimensions(rendered_image)):
61 continue
62 pixel_error = min(pixel_error,
63 calculate_pixel_error(rendered_image(xy),
64 max_image(neighboring_xy),
65 min_image(neighboring_xy)))
66
67 if pixel_error > 0:
68 max_error = max(max_error, pixel_error)
69 bad_pixels += 1
70 total_error += pixel_error
71
72 error_image(xy) = linear_interpolation(black, red, pixel_error)
73 else:
74 error_image(xy) = white
75
76 return ((total_error, max_error, bad_pixels), error_image)
77
78For each render test, there is a threshold value for `total_error`, :
79`passing_threshold`.
80
81If `passing_threshold >= 0 && total_error > passing_threshold`, then the test
82is a failure and is included in the report. if `passing_threshold == -1`, then
83the test always passes, but we do execute the test to verify that the driver
84does not crash.
85
86We generate a report with the following information for each test:
87
88 backend_name,render_test_name,max_error,bad_pixels,total_error
89
90in CSV format in the file `out.csv`. A HTML report of just the failing tests
91is written to the file `report.html`. This version includes four images for
92each test: `rendered_image`, `max_image`, `min_image`, and `error_image`, as
93well as the three metrics: `max_error`, `bad_pixels`, and `total_error`.
94
95
96
97
README_GENERATING_MODELS.md
1How SkQP Generates Render Test Models
2=====================================
3
4We will, at regular intervals, generate new models from the [master branch of
5Skia][1]. Here is how that process works:
6
70. Choose a commit to make the branch from
8
9 COMMIT=origin/master
10
111. Get the positively triaged results from Gold:
12
13 cd SKIA_SOURCE_DIRECTORY
14 git fetch origin
15 git checkout "$COMMIT"
16 python tools/skqp/get_gold_results.py "${COMMIT}~10" "$COMMIT"
17
18 This will produce a file `meta_YYYMMMDDD_HHHMMMSS_COMMIT_COMMIT.json` in
19 the current directory.
20
212. From a checkout of Skia's master branch, execute:
22
23 cd SKIA_SOURCE_DIRECTORY
24 git checkout "$COMMIT"
25 tools/skqp/cut_release META_JSON_FILE
26
27 This will create the following files:
28
29 platform_tools/android/apps/skqp/src/main/assets/files.checksum
30 platform_tools/android/apps/skqp/src/main/assets/skqp/rendertests.txt
31 platform_tools/android/apps/skqp/src/main/assets/skqp/unittests.txt
32
33 These three files can be commited to Skia to create a new commit. Make
34 `origin/skqp/dev` a parent of this commit (without merging it in), and
35 push this new commit to `origin/skqp/dev`:
36
37 tools/skqp/branch_skqp_dev.sh
38
39 Review and submit the change:
40
41 git push origin HEAD:refs/for/skqp/dev
42 bin/sysopen https://review.skia.org/$(bin/gerrit-number HEAD)
43
44 (Optional) Make a SkQP APK.
45
46 tools/skqp/docker_build_universal_apk.sh
47
48 (Optional) Test the SkQP APK:
49
50 adb uninstall org.skia.skqp
51 tools/skqp/test_apk.sh LOCATION/skqp-universal-debug.apk
52
53 (Once changes land) Upload the SkQP APK.
54
55 tools/skqp/upload_apk LOCATION/skqp-universal-debug.apk
56
57
58`tools/skqp/cut_release`
59------------------------
60
61This tool will call `make_gmkb.go` to generate the `m{ax,in}.png` files for
62each render test. Additionaly, a `models.txt` file enumerates all of the
63models.
64
65Then it calls `jitter_gms` to see which render tests pass the jitter test.
66`jitter_gms` respects the `bad_gms.txt` file by ignoring the render tests
67enumerated in that file. Tests which pass the jitter test are enumerated in
68the file `good.txt`, those that fail in the `bad.txt` file.
69
70Next, the `skqp/rendertests.txt` file is created. This file lists the render
71tests that will be executed by SkQP. These are the union of the tests
72enumerated in the `good.txt` and `bad.txt` files. If the render test is found
73in the `models.txt` file and the `good.txt` file, its per-test threshold is set
74to 0 (a later CL can manually change this, if needed). Otherwise, the
75threshold is set to -1; this indicated that the rendertest will be executed (to
76verify that the driver will not crash), but the output will not be compared
77against the model. Unnecessary models will be removed.
78
79Next, all of the files that represent the models are uploaded to cloud storage.
80A single checksum hash is kept in the `files.checksum` file. This is enough
81to re-download those files later, but we don't have to fill the git repository
82with a lot of binary data.
83
84Finally, a list of the current gpu unit tests is created and stored in
85`skqp/unittests.txt`.
86
87[1]: https://skia.googlesource.com/skia/+log/master "Skia Master Branch"
88[2]: https://gold.skia.org/search "Skia Gold Search"
89