mirror of https://github.com/minetest/irrlicht.git
300 lines
7.6 KiB
C++
300 lines
7.6 KiB
C++
// Copyright (C) 2002-2012 Nikolaus Gebhardt
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// This file is part of the "Irrlicht Engine".
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// For conditions of distribution and use, see copyright notice in irrlicht.h
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#include "IrrCompileConfig.h"
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#include "CTRTextureGouraud.h"
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#ifdef _IRR_COMPILE_WITH_SOFTWARE_
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namespace irr
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{
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namespace video
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{
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class CTRFlat : public CTRTextureGouraud
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{
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public:
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CTRFlat(IZBuffer* zbuffer)
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: CTRTextureGouraud(zbuffer)
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{
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#ifdef _DEBUG
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setDebugName("CTRFlat");
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#endif
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}
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//! draws an indexed triangle list
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virtual void drawIndexedTriangleList(S2DVertex* vertices, s32 vertexCount, const u16* indexList, s32 triangleCount) _IRR_OVERRIDE_
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{
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const S2DVertex *v1, *v2, *v3;
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u16 color;
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f32 tmpDiv; // temporary division factor
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f32 longest; // saves the longest span
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s32 height; // saves height of triangle
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u16* targetSurface; // target pointer where to plot pixels
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s32 spanEnd; // saves end of spans
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f32 leftdeltaxf; // amount of pixels to increase on left side of triangle
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f32 rightdeltaxf; // amount of pixels to increase on right side of triangle
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s32 leftx, rightx; // position where we are
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f32 leftxf, rightxf; // same as above, but as f32 values
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s32 span; // current span
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u16 *hSpanBegin, *hSpanEnd; // pointer used when plotting pixels
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core::rect<s32> TriangleRect;
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s32 leftZValue, rightZValue;
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s32 leftZStep, rightZStep;
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s32 spanZValue, spanZStep; // ZValues when drawing a span
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TZBufferType* zTarget, *spanZTarget; // target of ZBuffer;
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lockedSurface = (u16*)RenderTarget->getData();
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lockedZBuffer = ZBuffer->lock();
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for (s32 i=0; i<triangleCount; ++i)
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{
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v1 = &vertices[*indexList];
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++indexList;
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v2 = &vertices[*indexList];
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++indexList;
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v3 = &vertices[*indexList];
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++indexList;
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// back face culling
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if (BackFaceCullingEnabled)
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{
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s32 z = ((v3->Pos.X - v1->Pos.X) * (v3->Pos.Y - v2->Pos.Y)) -
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((v3->Pos.Y - v1->Pos.Y) * (v3->Pos.X - v2->Pos.X));
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if (z < 0)
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continue;
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}
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//near plane clipping
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if (v1->ZValue<0 && v2->ZValue<0 && v3->ZValue<0)
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continue;
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// sort for width for inscreen clipping
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if (v1->Pos.X > v2->Pos.X) swapVertices(&v1, &v2);
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if (v1->Pos.X > v3->Pos.X) swapVertices(&v1, &v3);
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if (v2->Pos.X > v3->Pos.X) swapVertices(&v2, &v3);
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if ((v1->Pos.X - v3->Pos.X) == 0)
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continue;
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TriangleRect.UpperLeftCorner.X = v1->Pos.X;
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TriangleRect.LowerRightCorner.X = v3->Pos.X;
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// sort for height for faster drawing.
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if (v1->Pos.Y > v2->Pos.Y) swapVertices(&v1, &v2);
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if (v1->Pos.Y > v3->Pos.Y) swapVertices(&v1, &v3);
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if (v2->Pos.Y > v3->Pos.Y) swapVertices(&v2, &v3);
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TriangleRect.UpperLeftCorner.Y = v1->Pos.Y;
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TriangleRect.LowerRightCorner.Y = v3->Pos.Y;
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if (!TriangleRect.isRectCollided(ViewPortRect))
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continue;
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// calculate height of triangle
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height = v3->Pos.Y - v1->Pos.Y;
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if (!height)
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continue;
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// calculate longest span
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longest = (v2->Pos.Y - v1->Pos.Y) / (f32)height * (v3->Pos.X - v1->Pos.X) + (v1->Pos.X - v2->Pos.X);
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spanEnd = v2->Pos.Y;
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span = v1->Pos.Y;
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leftxf = (f32)v1->Pos.X;
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rightxf = (f32)v1->Pos.X;
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leftZValue = v1->ZValue;
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rightZValue = v1->ZValue;
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color = v1->Color;
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targetSurface = lockedSurface + span * SurfaceWidth;
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zTarget = lockedZBuffer + span * SurfaceWidth;
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if (longest < 0.0f)
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{
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tmpDiv = 1.0f / (f32)(v2->Pos.Y - v1->Pos.Y);
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rightdeltaxf = (v2->Pos.X - v1->Pos.X) * tmpDiv;
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rightZStep = (s32)((v2->ZValue - v1->ZValue) * tmpDiv);
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tmpDiv = 1.0f / (f32)height;
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leftdeltaxf = (v3->Pos.X - v1->Pos.X) * tmpDiv;
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leftZStep = (s32)((v3->ZValue - v1->ZValue) * tmpDiv);
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}
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else
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{
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tmpDiv = 1.0f / (f32)height;
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rightdeltaxf = (v3->Pos.X - v1->Pos.X) * tmpDiv;
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rightZStep = (s32)((v3->ZValue - v1->ZValue) * tmpDiv);
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tmpDiv = 1.0f / (f32)(v2->Pos.Y - v1->Pos.Y);
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leftdeltaxf = (v2->Pos.X - v1->Pos.X) * tmpDiv;
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leftZStep = (s32)((v2->ZValue - v1->ZValue) * tmpDiv);
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}
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// do it twice, once for the first half of the triangle,
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// end then for the second half.
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for (s32 triangleHalf=0; triangleHalf<2; ++triangleHalf)
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{
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if (spanEnd > ViewPortRect.LowerRightCorner.Y)
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spanEnd = ViewPortRect.LowerRightCorner.Y;
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// if the span <0, than we can skip these spans,
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// and proceed to the next spans which are really on the screen.
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if (span < ViewPortRect.UpperLeftCorner.Y)
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{
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// we'll use leftx as temp variable
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if (spanEnd < ViewPortRect.UpperLeftCorner.Y)
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{
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leftx = spanEnd - span;
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span = spanEnd;
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}
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else
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{
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leftx = ViewPortRect.UpperLeftCorner.Y - span;
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span = ViewPortRect.UpperLeftCorner.Y;
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}
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leftxf += leftdeltaxf*leftx;
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rightxf += rightdeltaxf*leftx;
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targetSurface += SurfaceWidth*leftx;
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zTarget += SurfaceWidth*leftx;
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leftZValue += leftZStep*leftx;
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rightZValue += rightZStep*leftx;
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}
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// the main loop. Go through every span and draw it.
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while (span < spanEnd)
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{
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leftx = (s32)(leftxf);
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rightx = (s32)(rightxf + 0.5f);
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// perform some clipping
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// TODO: clipping is not correct when leftx is clipped.
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if (leftx<ViewPortRect.UpperLeftCorner.X)
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leftx = ViewPortRect.UpperLeftCorner.X;
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else
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if (leftx>ViewPortRect.LowerRightCorner.X)
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leftx = ViewPortRect.LowerRightCorner.X;
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if (rightx<ViewPortRect.UpperLeftCorner.X)
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rightx = ViewPortRect.UpperLeftCorner.X;
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else
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if (rightx>ViewPortRect.LowerRightCorner.X)
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rightx = ViewPortRect.LowerRightCorner.X;
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// draw the span
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if (rightx - leftx != 0)
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{
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tmpDiv = 1.0f / (rightx - leftx);
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spanZValue = leftZValue;
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spanZStep = (s32)((rightZValue - leftZValue) * tmpDiv);
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hSpanBegin = targetSurface + leftx;
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spanZTarget = zTarget + leftx;
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hSpanEnd = targetSurface + rightx;
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while (hSpanBegin < hSpanEnd)
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{
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if (spanZValue > *spanZTarget)
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{
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*spanZTarget = spanZValue;
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*hSpanBegin = color;
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}
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spanZValue += spanZStep;
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++hSpanBegin;
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++spanZTarget;
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}
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}
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leftxf += leftdeltaxf;
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rightxf += rightdeltaxf;
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++span;
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targetSurface += SurfaceWidth;
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zTarget += SurfaceWidth;
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leftZValue += leftZStep;
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rightZValue += rightZStep;
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}
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if (triangleHalf>0) // break, we've gout only two halves
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break;
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// setup variables for second half of the triangle.
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if (longest < 0.0f)
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{
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tmpDiv = 1.0f / (v3->Pos.Y - v2->Pos.Y);
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rightdeltaxf = (v3->Pos.X - v2->Pos.X) * tmpDiv;
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rightxf = (f32)v2->Pos.X;
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rightZValue = v2->ZValue;
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rightZStep = (s32)((v3->ZValue - v2->ZValue) * tmpDiv);
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}
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else
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{
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tmpDiv = 1.0f / (v3->Pos.Y - v2->Pos.Y);
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leftdeltaxf = (v3->Pos.X - v2->Pos.X) * tmpDiv;
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leftxf = (f32)v2->Pos.X;
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leftZValue = v2->ZValue;
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leftZStep = (s32)((v3->ZValue - v2->ZValue) * tmpDiv);
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}
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spanEnd = v3->Pos.Y;
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}
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}
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ZBuffer->unlock();
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}
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};
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} // end namespace video
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} // end namespace irr
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#endif // _IRR_COMPILE_WITH_SOFTWARE_
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namespace irr
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{
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namespace video
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{
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//! creates a flat triangle renderer
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ITriangleRenderer* createTriangleRendererFlat(IZBuffer* zbuffer)
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{
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#ifdef _IRR_COMPILE_WITH_SOFTWARE_
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return new CTRFlat(zbuffer);
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#else
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return 0;
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#endif // _IRR_COMPILE_WITH_SOFTWARE_
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}
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} // end namespace video
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} // end namespace irr
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