qmlcontrols/graphicaleffects/preserveaspect_core.vert

0001 /*
0002 SPDX-FileCopyrightText: 2021 Arjen Hiemstra <ahiemstra@heimr.nl>
0003
0004 SPDX-License-Identifier: LGPL-2.0-or-later
0005 */
0006
0007 // This shader performs UV coordinates that account for the aspect ratio of some
0008 // source as specified by the sourceSize uniform. The effective result is that
0009 // this results in behaviour similar to the "PreserveAspectFit" mode of QML Image.
0010
0011 uniform highp mat4 qt_Matrix;
0012
0013 uniform highp vec2 sourceSize;
0014
0015 in highp vec4 qt_Vertex;
0016 in highp vec2 qt_MultiTexCoord0;
0017
0018 out highp vec2 qt_TexCoord0;
0019
0020 void main() {
0021     highp float scale = min(targetSize.x / sourceSize.x, targetSize.y / sourceSize.y);
0022
0023     highp vec2 newSize = sourceSize * scale;
0024     highp vec2 newOffset = (targetSize - newSize) / 2.0;
0025     highp vec2 uvOffset = (1.0 / newSize) * newOffset;
0026
0027     qt_TexCoord0 = -uvOffset + (targetSize / newSize) * qt_MultiTexCoord0;
0028     gl_Position = qt_Matrix * qt_Vertex;
0029 }