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++ // Copyright (C) 2024 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
++
++ #if QSHADER_VIEW_COUNT >= 2
++ #define SAMPLE(uv) texture(DEPTH_TEXTURE, vec3(uv, VIEW_INDEX))
++ #else
++ #define SAMPLE(uv) texture(DEPTH_TEXTURE, uv)
++ #endif
++
++ void MAIN()
++ {
++ // not really using the texture array version, unless multiview rendering is active,
++ // nonetheless this test verifies that QSHADER_VIEW_COUNT is defined etc.
++ #if QSHADER_VIEW_COUNT >= 2
++ vec2 uv = (gl_FragCoord.xy) / vec2(textureSize(DEPTH_TEXTURE, 0).xy);
++ vec4 depthSample = texture(DEPTH_TEXTURE, vec3(uv, VIEW_INDEX));
++ #else
++ vec2 uv = (gl_FragCoord.xy) / vec2(textureSize(DEPTH_TEXTURE, 0));
++ vec4 depthSample = texture(DEPTH_TEXTURE, uv);
++ #endif
++
++ // test that the #define lines are handled correctly; this is a typical
++ // approach to simplify the above without having to repeat the #if
++ // QSHADER_VIEW_COUNT everywhere.
++ depthSample = SAMPLE(uv);
++
++ float zNear = CAMERA_PROPERTIES.x;
++ float zFar = CAMERA_PROPERTIES.y;
++ float zRange = zFar - zNear;
++
++ float z_n = 2.0 * depthSample.r - 1.0;
++ float d = 2.0 * zNear * zFar / (zFar + zNear - z_n * zRange);
++ d /= zFar;
++
++ FRAGCOLOR = vec4(d, d, d, 1.0);
++ }