1 ------------------------------------------------------------------------- 2 drawElements Quality Program Test Specification 3 ----------------------------------------------- 4 5 Copyright 2014 The Android Open Source Project 6 7 Licensed under the Apache License, Version 2.0 (the "License"); 8 you may not use this file except in compliance with the License. 9 You may obtain a copy of the License at 10 11 http://www.apache.org/licenses/LICENSE-2.0 12 13 Unless required by applicable law or agreed to in writing, software 14 distributed under the License is distributed on an "AS IS" BASIS, 15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 See the License for the specific language governing permissions and 17 limitations under the License. 18 ------------------------------------------------------------------------- 19 Sample shading tests 20 21 Tests: 22 + dEQP-GLES31.functional.sample_shading 23 24 Includes: 25 + Visual verification of OES_sample_shading 26 - per sample color 27 - per sample discard 28 + State queries 29 30 Excludes: 31 + Rendering to every supported render buffer sample count / format 32 + Rendering to every supported multisample texture sample count / format 33 34 Description: 35 36 state_query.* tests verify that the state returned by different query functions 37 is valid. state_query.min_sample_shading_value_clamping test verifies 38 MIN_SAMPLE_SHADING state is clamped when it is specified with glMinSampleShading 39 function. 40 41 min_sample_shading.* tests render a high frequency pattern with different 42 MIN_SAMPLE_SHADING values. *_color cases render pattern by rendering black or 43 white in the fragment shader depending on the pattern function sign. *_discard 44 cases render pattern by the clearing image to black, outputting white in the 45 fragment shader, and discarding the fragment if function sign is negative. Each 46 test iteration sets MIN_SAMPLE_SHADING_VALUE to guarantee a certain number of 47 individual samples and draws the pattern. 48 49 Averaging N uniformly random binary values (pattern output function) and 50 averaging them will result in a discrete normal-like distribution. The number of 51 samples N can now be calculated from the distribution with: the number of 52 distinct points with non-zero probability - 1. A sufficiently high frequency 53 function is assumed to have similar effect to the uniform random. Hence, if the 54 number of different shades in the result image is less or equal to the 55 guaranteed sample count, the pixels did not contain the guaranteed amount of 56 independent samples, i.e. result image is invalid. 57 58 Since the tests analyze the resolved multisample image when rendering to the 59 default framebuffer or to a renderbuffer, implementations that do not resolve 60 multisample buffers with a box filter (simple average) may result in false 61 positives. False positive may occur if distinct pixels with identical filter 62 sample coverage ratios can be mapped to distinct values. Tests rendering to a 63 multisample texture do not use an implementation defined multisample resolution 64 and thus do not produce false positives. 65
