From f945fd4ce4feb4f5b0af60510fe656e36f0a836f Mon Sep 17 00:00:00 2001 From: David Williams Date: Thu, 29 May 2014 12:38:43 +0200 Subject: [PATCH] Work on example to decode vertices on the GPU. --- examples/DecodeOnGPU/main.cpp | 57 ++++++++++++++++++++++++++++++++-- examples/common/OpenGLWidget.h | 19 +++++++----- 2 files changed, 67 insertions(+), 9 deletions(-) diff --git a/examples/DecodeOnGPU/main.cpp b/examples/DecodeOnGPU/main.cpp index a13da717..83950b1b 100644 --- a/examples/DecodeOnGPU/main.cpp +++ b/examples/DecodeOnGPU/main.cpp @@ -66,6 +66,58 @@ void createSphereInVolume(SimpleVolume& 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. diff --git a/examples/common/OpenGLWidget.h b/examples/common/OpenGLWidget.h index 930cb3d8..a0150556 100644 --- a/examples/common/OpenGLWidget.h +++ b/examples/common/OpenGLWidget.h @@ -53,8 +53,8 @@ public: OpenGLWidget(QWidget *parent); // Convert a PolyVox mesh to OpenGL index/vertex buffers. Inlined because it's templatised. - template - void addMesh(const MeshType& surfaceMesh, const PolyVox::Vector3DInt32& translation = PolyVox::Vector3DInt32(0, 0, 0), float scale = 1.0f) + template + 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); }