167 lines
7.3 KiB
C++
167 lines
7.3 KiB
C++
/*******************************************************************************
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Copyright (c) 2005-2009 David Williams
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source
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distribution.
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*******************************************************************************/
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#include "OpenGLWidget.h"
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#include "PolyVox/CubicSurfaceExtractor.h"
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#include "PolyVox/MarchingCubesSurfaceExtractor.h"
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#include "PolyVox/Mesh.h"
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#include "PolyVox/PagedVolume.h"
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#include <QApplication>
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//Use the PolyVox namespace
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using namespace PolyVox;
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void createSphereInVolume(PagedVolume<uint8_t>& volData, float fRadius)
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{
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//This vector hold the position of the center of the volume
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Vector3DFloat v3dVolCenter(volData.getWidth() / 2, volData.getHeight() / 2, volData.getDepth() / 2);
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//This three-level for loop iterates over every voxel in the volume
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for (int z = 0; z < volData.getDepth(); z++)
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{
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for (int y = 0; y < volData.getHeight(); y++)
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{
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for (int x = 0; x < volData.getWidth(); x++)
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{
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//Store our current position as a vector...
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Vector3DFloat v3dCurrentPos(x,y,z);
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//And compute how far the current position is from the center of the volume
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float fDistToCenter = (v3dCurrentPos - v3dVolCenter).length();
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uint8_t uVoxelValue = 0;
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//If the current voxel is less than 'radius' units from the center then we make it solid.
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if(fDistToCenter <= fRadius)
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{
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//Our new voxel value
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uVoxelValue = 255;
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}
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//Wrte the voxel value into the volume
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volData.setVoxelAt(x, y, z, uVoxelValue);
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}
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}
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}
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}
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OpenGLMeshData buildOpenGLMeshData(const PolyVox::Mesh< PolyVox::MarchingCubesVertex< uint8_t > >& surfaceMesh, const PolyVox::Vector3DInt32& translation = PolyVox::Vector3DInt32(0, 0, 0), float scale = 1.0f)
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{
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// Convienient access to the vertices and indices
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const auto& vecIndices = surfaceMesh.getIndices();
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const auto& vecVertices = surfaceMesh.getVertices();
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// This struct holds the OpenGL properties (buffer handles, etc) which will be used
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// to render our mesh. We copy the data from the PolyVox mesh into this structure.
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OpenGLMeshData meshData;
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// Create the VAO for the mesh
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glGenVertexArrays(1, &(meshData.vertexArrayObject));
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glBindVertexArray(meshData.vertexArrayObject);
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// The GL_ARRAY_BUFFER will contain the list of vertex positions
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glGenBuffers(1, &(meshData.vertexBuffer));
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glBindBuffer(GL_ARRAY_BUFFER, meshData.vertexBuffer);
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glBufferData(GL_ARRAY_BUFFER, vecVertices.size() * sizeof(MarchingCubesVertex< uint8_t >), vecVertices.data(), GL_STATIC_DRAW);
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// and GL_ELEMENT_ARRAY_BUFFER will contain the indices
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glGenBuffers(1, &(meshData.indexBuffer));
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glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, meshData.indexBuffer);
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glBufferData(GL_ELEMENT_ARRAY_BUFFER, vecIndices.size() * sizeof(uint32_t), vecIndices.data(), GL_STATIC_DRAW);
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// Every surface extractor outputs valid positions for the vertices, so tell OpenGL how these are laid out
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glEnableVertexAttribArray(0); // Attrib '0' is the vertex positions
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glVertexAttribIPointer(0, 3, GL_UNSIGNED_SHORT, sizeof(MarchingCubesVertex< uint8_t >), (GLvoid*)(offsetof(MarchingCubesVertex< uint8_t >, encodedPosition))); //take the first 3 floats from every sizeof(decltype(vecVertices)::value_type)
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// Some surface extractors also generate normals, so tell OpenGL how these are laid out. If a surface extractor
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// does not generate normals then nonsense values are written into the buffer here and sghould be ignored by the
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// shader. This is mostly just to simplify this example code - in a real application you will know whether your
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// chosen surface extractor generates normals and can skip uploading them if not.
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glEnableVertexAttribArray(1); // Attrib '1' is the vertex normals.
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glVertexAttribIPointer(1, 1, GL_UNSIGNED_SHORT, sizeof(MarchingCubesVertex< uint8_t >), (GLvoid*)(offsetof(MarchingCubesVertex< uint8_t >, encodedNormal)));
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// Finally a surface extractor will probably output additional data. This is highly application dependant. For this example code
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// we're just uploading it as a set of bytes which we can read individually, but real code will want to do something specialised here.
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glEnableVertexAttribArray(2); //We're talking about shader attribute '2'
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GLint size = (std::min)(sizeof(uint8_t), size_t(4)); // Can't upload more that 4 components (vec4 is GLSL's biggest type)
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glVertexAttribIPointer(2, size, GL_UNSIGNED_BYTE, sizeof(MarchingCubesVertex< uint8_t >), (GLvoid*)(offsetof(MarchingCubesVertex< uint8_t >, data)));
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// We're done uploading and can now unbind.
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glBindVertexArray(0);
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// A few additional properties can be copied across for use during rendering.
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meshData.noOfIndices = vecIndices.size();
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meshData.translation = QVector3D(translation.getX(), translation.getY(), translation.getZ());
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meshData.scale = scale;
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// Set 16 or 32-bit index buffer size.
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meshData.indexType = sizeof(PolyVox::Mesh< PolyVox::MarchingCubesVertex< uint8_t > >::IndexType) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT;
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return meshData;
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}
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int main(int argc, char *argv[])
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{
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//Create and show the Qt OpenGL window
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QApplication app(argc, argv);
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OpenGLWidget openGLWidget(0);
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openGLWidget.show();
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QSharedPointer<QGLShaderProgram> shader(new QGLShaderProgram);
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if (!shader->addShaderFromSourceFile(QGLShader::Vertex, ":/decode.vert"))
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{
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std::cerr << shader->log().toStdString() << std::endl;
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exit(EXIT_FAILURE);
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}
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if (!shader->addShaderFromSourceFile(QGLShader::Fragment, ":/decode.frag"))
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{
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std::cerr << shader->log().toStdString() << std::endl;
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exit(EXIT_FAILURE);
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}
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openGLWidget.setShader(shader);
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//Create an empty volume and then place a sphere in it
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PagedVolume<uint8_t> volData(PolyVox::Region(Vector3DInt32(0, 0, 0), Vector3DInt32(63, 63, 63)));
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createSphereInVolume(volData, 30);
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// Extract the surface for the specified region of the volume. Uncomment the line for the kind of surface extraction you want to see.
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//auto mesh = extractCubicMesh(&volData, volData.getEnclosingRegion());
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auto mesh = extractMarchingCubesMesh(&volData, volData.getEnclosingRegion());
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// The surface extractor outputs the mesh in an efficient compressed format which is not directly suitable for rendering. The easiest approach is to
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// decode this on the CPU as shown below, though more advanced applications can upload the compressed mesh to the GPU and decompress in shader code.
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//auto decodedMesh = decodeMesh(mesh);
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//Pass the surface to the OpenGL window
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OpenGLMeshData meshData = buildOpenGLMeshData(mesh);
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openGLWidget.addMeshData(meshData);
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openGLWidget.setViewableRegion(volData.getEnclosingRegion());
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//Run the message pump.
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return app.exec();
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} |