mirror of
https://github.com/AquariaOSE/Aquaria.git
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127 lines
2.9 KiB
C++
127 lines
2.9 KiB
C++
/*
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Copyright (C) 2007, 2010 - Bit-Blot
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This file is part of Aquaria.
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Aquaria is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include "Strand.h"
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#include "RenderBase.h"
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Strand::Strand(const Vector &position, size_t segs, float dist)
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: RenderObject()
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, points(segs)
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, gpubuf(GPUBUF_DYNAMIC | GPUBUF_VERTEXBUF)
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, dist(dist)
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{
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assert(segs);
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cull = false;
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for (size_t i = 0; i < segs; i++)
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points[i] = position;
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}
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void Strand::updatePoints()
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{
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Vector last = position;
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const float distsq = sqr(dist);
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const size_t N = points.size();
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for(size_t i = 0; i < N; ++i)
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{
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Vector pt = points[i];
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const Vector diff = last - pt;
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last = pt;
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const float sqrLength = diff.getSquaredLength2D();
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if (sqrLength < distsq)
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continue;
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Vector useDiff = diff;
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useDiff.setLength2D(dist);
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Vector reallyUseDiff = diff - useDiff;
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points[i] = pt + reallyUseDiff;
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}
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}
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void Strand::onUpdate(float dt)
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{
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RenderObject::onUpdate(dt);
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updatePoints();
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const size_t N = points.size();
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do
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{
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const size_t bytes = (N+1) * 6 * sizeof(float); // +1 for the initial origin vertex
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float *p = (float*)gpubuf.beginWrite(GPUBUFTYPE_VEC2_RGBA, bytes, GPUACCESS_DEFAULT);
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// Note: We're rewriting all of the vertex data here.
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// Ideally we'd only rewrite position data since vertex colors never change,
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// but currently this is to keep buffer layouts simple.
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const float factor = 1.0f / 50.0f;
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const size_t colorLimit = N<50 ? N : 50;
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const Vector falloff = color * factor;
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const float falloffAlpha = 1.0f / float(N);
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float a = 1.0f;
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Vector c = color;
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// initial vertex (this is the +1)
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*p++ = position.x;
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*p++ = position.y;
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*p++ = c.x;
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*p++ = c.y;
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*p++ = c.z;
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*p++ = a;
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size_t i;
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for(i = 0; i < colorLimit; ++i)
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{
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*p++ = points[i].x;
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*p++ = points[i].y;
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*p++ = c.x;
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*p++ = c.y;
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*p++ = c.z;
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*p++ = a;
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c -= falloff;
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a -= falloffAlpha;
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}
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for( ; i < N; ++i)
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{
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*p++ = points[i].x;
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*p++ = points[i].y;
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*p++ = 0.0f;
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*p++ = 0.0f;
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*p++ = 0.0f;
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*p++ = a;
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a -= falloffAlpha;
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}
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}
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while(!gpubuf.commitWrite());
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}
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void Strand::onRender(const RenderState& rs) const
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{
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glTranslatef(-position.x, -position.y, 0);
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glLineWidth(1);
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gpubuf.apply();
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glDrawArrays(GL_LINE_STRIP, 0, GLsizei(points.size() + 1));
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}
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