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Work on example to decode vertices on the GPU.

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This commit is contained in:
David Williams 2014-05-29 12:38:43 +02:00
parent b635e9d29d
commit f945fd4ce4
2 changed files with 67 additions and 9 deletions
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57
examples/DecodeOnGPU/main.cpp
View File

@ -66,6 +66,58 @@ void createSphereInVolume(SimpleVolume<uint8_t>& volData, float fRadius)
}
}
OpenGLMeshData buildOpenGLMeshData(const PolyVox::Mesh< PolyVox::Vertex< uint8_t > >& surfaceMesh, const PolyVox::Vector3DInt32& translation = PolyVox::Vector3DInt32(0, 0, 0), float scale = 1.0f)
{
// Convienient access to the vertices and indices
const auto& vecIndices = surfaceMesh.getIndices();
const auto& vecVertices = surfaceMesh.getVertices();
// This struct holds the OpenGL properties (buffer handles, etc) which will be used
// to render our mesh. We copy the data from the PolyVox mesh into this structure.
OpenGLMeshData meshData;
// Create the VAO for the mesh
glGenVertexArrays(1, &(meshData.vertexArrayObject));
glBindVertexArray(meshData.vertexArrayObject);
// The GL_ARRAY_BUFFER will contain the list of vertex positions
glGenBuffers(1, &(meshData.vertexBuffer));
glBindBuffer(GL_ARRAY_BUFFER, meshData.vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, vecVertices.size() * sizeof(Vertex< uint8_t >), vecVertices.data(), GL_STATIC_DRAW);
// and GL_ELEMENT_ARRAY_BUFFER will contain the indices
glGenBuffers(1, &(meshData.indexBuffer));
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, meshData.indexBuffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, vecIndices.size() * sizeof(uint32_t), vecIndices.data(), GL_STATIC_DRAW);
// Every surface extractor outputs valid positions for the vertices, so tell OpenGL how these are laid out
glEnableVertexAttribArray(0); // Attrib '0' is the vertex positions
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex< uint8_t >), (GLvoid*)(offsetof(Vertex< uint8_t >, position))); //take the first 3 floats from every sizeof(decltype(vecVertices)::value_type)
// Some surface extractors also generate normals, so tell OpenGL how these are laid out. If a surface extractor
// does not generate normals then nonsense values are written into the buffer here and sghould be ignored by the
// shader. This is mostly just to simplify this example code - in a real application you will know whether your
// chosen surface extractor generates normals and can skip uploading them if not.
glEnableVertexAttribArray(1); // Attrib '1' is the vertex normals.
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex< uint8_t >), (GLvoid*)(offsetof(Vertex< uint8_t >, normal)));
// Finally a surface extractor will probably output additional data. This is highly application dependant. For this example code
// 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.
glEnableVertexAttribArray(2); //We're talking about shader attribute '2'
GLint size = (std::min)(sizeof(uint8_t), size_t(4)); // Can't upload more that 4 components (vec4 is GLSL's biggest type)
glVertexAttribIPointer(2, size, GL_UNSIGNED_BYTE, sizeof(Vertex< uint8_t >), (GLvoid*)(offsetof(Vertex< uint8_t >, data)));
// We're done uploading and can now unbind.
glBindVertexArray(0);
// A few additional properties can be copied across for use during rendering.
meshData.noOfIndices = vecIndices.size();
meshData.translation = QVector3D(translation.getX(), translation.getY(), translation.getZ());
meshData.scale = scale;
return meshData;
}
int main(int argc, char *argv[])
{
//Create and show the Qt OpenGL window
@ -86,8 +138,9 @@ int main(int argc, char *argv[])
auto decodedMesh = decode(mesh);
//Pass the surface to the OpenGL window
openGLWidget.addMesh(decodedMesh);
//openGLWidget.addMesh(mesh2);
OpenGLMeshData meshData = buildOpenGLMeshData(decodedMesh);
openGLWidget.addMeshData(meshData);
openGLWidget.setViewableRegion(volData.getEnclosingRegion());
//Run the message pump.

19
examples/common/OpenGLWidget.h
View File

@ -53,8 +53,8 @@ public:
OpenGLWidget(QWidget *parent);
// Convert a PolyVox mesh to OpenGL index/vertex buffers. Inlined because it's templatised.
template <typename MeshType>
void addMesh(const MeshType& surfaceMesh, const PolyVox::Vector3DInt32& translation = PolyVox::Vector3DInt32(0, 0, 0), float scale = 1.0f)
template <typename DataType>
void addMesh(const PolyVox::Mesh< PolyVox::Vertex< DataType > >& surfaceMesh, const PolyVox::Vector3DInt32& translation = PolyVox::Vector3DInt32(0, 0, 0), float scale = 1.0f)
{
// Convienient access to the vertices and indices
const auto& vecIndices = surfaceMesh.getIndices();
@ -71,7 +71,7 @@ public:
// The GL_ARRAY_BUFFER will contain the list of vertex positions
glGenBuffers(1, &(meshData.vertexBuffer));
glBindBuffer(GL_ARRAY_BUFFER, meshData.vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, vecVertices.size() * sizeof(typename MeshType::VertexType), vecVertices.data(), GL_STATIC_DRAW);
glBufferData(GL_ARRAY_BUFFER, vecVertices.size() * sizeof(Vertex< DataType >), vecVertices.data(), GL_STATIC_DRAW);
// and GL_ELEMENT_ARRAY_BUFFER will contain the indices
glGenBuffers(1, &(meshData.indexBuffer));
@ -80,20 +80,20 @@ public:
// Every surface extractor outputs valid positions for the vertices, so tell OpenGL how these are laid out
glEnableVertexAttribArray(0); // Attrib '0' is the vertex positions
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(typename MeshType::VertexType), (GLvoid*)(offsetof(typename MeshType::VertexType, position))); //take the first 3 floats from every sizeof(decltype(vecVertices)::value_type)
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex< DataType >), (GLvoid*)(offsetof(Vertex< DataType >, position))); //take the first 3 floats from every sizeof(decltype(vecVertices)::value_type)
// Some surface extractors also generate normals, so tell OpenGL how these are laid out. If a surface extractor
// does not generate normals then nonsense values are written into the buffer here and sghould be ignored by the
// shader. This is mostly just to simplify this example code - in a real application you will know whether your
// chosen surface extractor generates normals and can skip uploading them if not.
glEnableVertexAttribArray(1); // Attrib '1' is the vertex normals.
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(typename MeshType::VertexType), (GLvoid*)(offsetof(typename MeshType::VertexType, normal)));
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex< DataType >), (GLvoid*)(offsetof(Vertex< DataType >, normal)));
// Finally a surface extractor will probably output additional data. This is highly application dependant. For this example code
// 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.
glEnableVertexAttribArray(2); //We're talking about shader attribute '2'
GLint size = (std::min)(sizeof(typename MeshType::VertexType::DataType), size_t(4)); // Can't upload more that 4 components (vec4 is GLSL's biggest type)
glVertexAttribIPointer(2, size, GL_UNSIGNED_BYTE, sizeof(typename MeshType::VertexType), (GLvoid*)(offsetof(typename MeshType::VertexType, data)));
GLint size = (std::min)(sizeof(DataType), size_t(4)); // Can't upload more that 4 components (vec4 is GLSL's biggest type)
glVertexAttribIPointer(2, size, GL_UNSIGNED_BYTE, sizeof(Vertex< DataType >), (GLvoid*)(offsetof(Vertex< DataType >, data)));
// We're done uploading and can now unbind.
glBindVertexArray(0);
@ -104,6 +104,11 @@ public:
meshData.scale = scale;
// Now add the mesh to the list of meshes to render.
addMeshData(meshData);
}
void addMeshData(OpenGLMeshData meshData)
{
mMeshData.push_back(meshData);
}