148 lines
5.2 KiB
C++
148 lines
5.2 KiB
C++
//============================================================================
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// Copyright (c) Kitware, Inc.
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// All rights reserved.
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// See LICENSE.txt for details.
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//
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// This software is distributed WITHOUT ANY WARRANTY; without even
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// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the above copyright notice for more information.
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//============================================================================
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#include <vtkm/rendering/LineRenderer.h>
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#include <vtkm/Transform3D.h>
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#include <vtkm/cont/TryExecute.h>
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#include <vtkm/worklet/DispatcherMapField.h>
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#include <vtkm/worklet/WorkletMapField.h>
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namespace vtkm
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{
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namespace rendering
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{
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LineRenderer::LineRenderer(const vtkm::rendering::Canvas* canvas,
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vtkm::Matrix<vtkm::Float32, 4, 4> transform)
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: Canvas(canvas)
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, Transform(transform)
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{
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}
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void LineRenderer::RenderLine(const vtkm::Vec2f_64& point0,
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const vtkm::Vec2f_64& point1,
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vtkm::Float32 lineWidth,
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const vtkm::rendering::Color& color)
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{
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RenderLine(vtkm::make_Vec(point0[0], point0[1], 0.0),
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vtkm::make_Vec(point1[0], point1[1], 0.0),
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lineWidth,
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color);
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}
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void LineRenderer::RenderLine(const vtkm::Vec3f_64& point0,
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const vtkm::Vec3f_64& point1,
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vtkm::Float32 vtkmNotUsed(lineWidth),
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const vtkm::rendering::Color& color)
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{
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vtkm::Vec3f_32 p0 = TransformPoint(point0);
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vtkm::Vec3f_32 p1 = TransformPoint(point1);
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vtkm::Id x0 = static_cast<vtkm::Id>(vtkm::Round(p0[0]));
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vtkm::Id y0 = static_cast<vtkm::Id>(vtkm::Round(p0[1]));
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vtkm::Float32 z0 = static_cast<vtkm::Float32>(p0[2]);
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vtkm::Id x1 = static_cast<vtkm::Id>(vtkm::Round(p1[0]));
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vtkm::Id y1 = static_cast<vtkm::Id>(vtkm::Round(p1[1]));
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vtkm::Float32 z1 = static_cast<vtkm::Float32>(p1[2]);
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vtkm::Id dx = vtkm::Abs(x1 - x0), sx = x0 < x1 ? 1 : -1;
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vtkm::Id dy = -vtkm::Abs(y1 - y0), sy = y0 < y1 ? 1 : -1;
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vtkm::Id err = dx + dy, err2 = 0;
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const vtkm::Id xStart = x0;
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const vtkm::Id yStart = y0;
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const vtkm::Float32 pdist = vtkm::Sqrt(vtkm::Float32(dx * dx) + vtkm::Float32(dy * dy));
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auto colorPortal =
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vtkm::rendering::Canvas::ColorBufferType(Canvas->GetColorBuffer()).WritePortal();
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auto depthPortal =
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vtkm::rendering::Canvas::DepthBufferType(Canvas->GetDepthBuffer()).WritePortal();
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vtkm::Vec4f_32 colorC = color.Components;
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while (x0 >= 0 && x0 < Canvas->GetWidth() && y0 >= 0 && y0 < Canvas->GetHeight())
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{
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vtkm::Float32 deltaX = static_cast<vtkm::Float32>(x0 - xStart);
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vtkm::Float32 deltaY = static_cast<vtkm::Float32>(y0 - yStart);
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// Depth is wrong, but its far less wrong that it used to be.
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// These depth values are in screen space, which have been
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// potentially tranformed by a perspective correction.
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// To interpolated the depth correctly, there must be a perspective correction.
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// I haven't looked, but the wireframmer probably suffers from this too.
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// Additionally, this should not happen on the CPU. Annotations take
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// far longer than the the geometry.
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vtkm::Float32 t = pdist == 0.f ? 1.0f : vtkm::Sqrt(deltaX * deltaX + deltaY * deltaY) / pdist;
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t = vtkm::Min(1.f, vtkm::Max(0.f, t));
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vtkm::Float32 z = vtkm::Lerp(z0, z1, t);
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vtkm::Id index = y0 * Canvas->GetWidth() + x0;
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vtkm::Vec4f_32 currentColor = colorPortal.Get(index);
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vtkm::Float32 currentZ = depthPortal.Get(index);
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bool blend = currentColor[3] < 1.f && z > currentZ;
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if (currentZ > z || blend)
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{
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vtkm::Vec4f_32 writeColor = colorC;
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vtkm::Float32 depth = z;
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if (blend)
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{
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// If there is any transparency, all alphas
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// have been pre-mulitplied
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vtkm::Float32 alpha = (1.f - currentColor[3]);
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writeColor[0] = currentColor[0] + colorC[0] * alpha;
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writeColor[1] = currentColor[1] + colorC[1] * alpha;
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writeColor[2] = currentColor[2] + colorC[2] * alpha;
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writeColor[3] = 1.f * alpha + currentColor[3]; // we are always drawing opaque lines
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// keep the current z. Line z interpolation is not accurate
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// Matt: this is correct. Interpolation is wrong
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depth = currentZ;
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}
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depthPortal.Set(index, depth);
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colorPortal.Set(index, writeColor);
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}
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if (x0 == x1 && y0 == y1)
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{
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break;
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}
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err2 = err * 2;
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if (err2 >= dy)
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{
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err += dy;
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x0 += sx;
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}
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if (err2 <= dx)
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{
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err += dx;
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y0 += sy;
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}
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}
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}
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vtkm::Vec3f_32 LineRenderer::TransformPoint(const vtkm::Vec3f_64& point) const
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{
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vtkm::Vec4f_32 temp(static_cast<vtkm::Float32>(point[0]),
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static_cast<vtkm::Float32>(point[1]),
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static_cast<vtkm::Float32>(point[2]),
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1.0f);
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temp = vtkm::MatrixMultiply(Transform, temp);
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vtkm::Vec3f_32 p;
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for (vtkm::IdComponent i = 0; i < 3; ++i)
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{
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p[i] = static_cast<vtkm::Float32>(temp[i] / temp[3]);
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}
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p[0] = (p[0] * 0.5f + 0.5f) * static_cast<vtkm::Float32>(Canvas->GetWidth());
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p[1] = (p[1] * 0.5f + 0.5f) * static_cast<vtkm::Float32>(Canvas->GetHeight());
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p[2] = (p[2] * 0.5f + 0.5f) - 0.001f;
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return p;
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}
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}
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} // namespace vtkm::rendering
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