c44ee2beb3
The plain scaling is rather rough, and in fact drawing a scaled bitmap the normal way gives much better results (because OutputDevice pre-scales the bitmap before it's drawn). This one may be a bit slow perhaps, but hopefully nobody there's no code that'd extensively use bitmap drawing with custom transformations (wishful thinking). Change-Id: I83e05307adfaeac0ed0757f1a0b2603f64caf8f8
57 lines
1.5 KiB
GLSL
57 lines
1.5 KiB
GLSL
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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/* TODO Use textureOffset for newest version of GLSL */
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uniform sampler2D sampler;
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uniform int xscale;
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uniform int yscale;
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uniform float xstep;
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uniform float ystep;
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uniform float ratio; // = 1.0/(xscale*yscale)
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varying vec2 tex_coord;
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// This mode makes the scaling work like maskedTextureFragmentShader.glsl
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// (instead of like plain textureVertexShader.glsl).
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#ifdef MASKED
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uniform sampler2D mask;
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#endif
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/*
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Just make the resulting color the average of all the source pixels
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(which is an area (xscale)x(yscale) ).
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*/
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void main(void)
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{
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vec4 sum = vec4( 0.0, 0.0, 0.0, 0.0 );
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vec2 offset = vec2( 0.0, 0.0 );
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for( int y = 0; y < yscale; ++y )
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{
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for( int x = 0; x < xscale; ++x )
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{
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#ifndef MASKED
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sum += texture2D( sampler, tex_coord.st + offset );
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#else
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vec4 texel;
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texel = texture2D( sampler, tex_coord.st + offset );
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texel.a = 1.0 - texture2D( mask, tex_coord.st + offset ).r;
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sum += texel;
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#endif
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offset.x += xstep;
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}
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offset.y += ystep;
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offset.x = 0.0;
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}
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sum *= ratio;
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gl_FragColor = sum;
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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