## On this page # Test014 Last update: 16.07.2025 Scaled and textured spheres This example demonstrates the displacement and scaling pipeline. A grid of spheres is created using proxy geometry consisting of a single quad. Quads are instanced via scaling and translation before being rendered using a billboard sphere shader. <script src="./ansys251/nexus/viewer-loader.js"></script> /\* \* Copyright 2018-2021 ANSYS, Inc. Unauthorized use, distribution, or duplication is prohibited. \* \* Restricted Rights Legend \* \* Use, duplication, or disclosure of this \* software and its documentation by the \* Government is subject to restrictions as \* set forth in subdivision \[(b)(3)(ii)\] of \* the Rights in Technical Data and Computer \* Software clause at 52.227-7013. \*/ \#include <vector> \#include <cstdlib> \#include "GLTFWriter.h" \#include "test.h" using namespace ANSYS::AVZ; // Size/textured points TESTFUNC(ScaledPoints) { [GLTFWriter::GLTF](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_g_l_t_f.xhtml) *gltf = GLTFWriter::GLTF::Create("MyApp", "1.0", functionName.c_str(), type); if (!gltf) throw std::runtime_error("Can't create GLTF"); // TEXTURE std::vector<unsigned char> colors; colors.push_back(0); colors.push_back(0); colors.push_back(255); // blue colors.push_back(0); colors.push_back(255); colors.push_back(255); // cyan colors.push_back(0); colors.push_back(255); colors.push_back(0); // green colors.push_back(255); colors.push_back(255); colors.push_back(0); // yellow colors.push_back(255); colors.push_back(0); colors.push_back(0); // red [GLTFWriter::Texture](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_texture.xhtml) *rainbowGradientTexture = GLTFWriter::Texture::Create(gltf, GLTFWriter::Texture::TF_RGB, (unsigned int)colors.size() / 3, &colors[0], false); // Use a quad proxy geometry for the spheres const std::vector<float> proxy_verts = { -1.f,1.f,0.f, 1.f,1.f,0.f, 1.f,-1.f,0.f, -1.f,-1.f,0.f }; const std::vector<unsigned short> proxy_conn = { 0,3,2, 0,2,1 }; // Build the various arrays const float tex_coord_min = 0.f; const float tex_coord_max = 10.f; std::vector<float> vertices; std::vector<unsigned short> triangles; std::vector<float> tex_coords; std::vector<float> point_disp_scale; // Test the scaled/textured/positioned spheres path // Uses the DisplacementScale attribute (dx,dy,dz,s) to scale 2D proxy // geometry, translate it by dx,dy,dz and render it with a sphere shader, // colored and textured the same as other gltf geometry. The proxy geometry // should be 2D and centered about 0,0,0 with unity size \[-1,1\]. It will be // drawn using a billboard technique so the geometry should be in the x,y plane. for(size\_t j = 0; j < 10; j++) { float y = (j * 0.1f) - 0.5f; for(size\_t i = 0; i < 10; i++) { float x = (i * 0.1f) - 0.5f; float z = 0.f; float scale = j * 0.005; // make a copy of the quad and place it into the vertex/triangle arrays auto vertex_index = vertices.size() / 3; for(const auto idx : proxy_conn) triangles.push_back(idx + vertex_index); vertices.insert(vertices.end(), proxy_verts.begin(), proxy_verts.end()); // Point location and size (applied to each proxy quad) for(size\_t vert = 0; vert < proxy_verts.size() / 3; vert++) { point_disp_scale.push_back(x); point_disp_scale.push_back(y); point_disp_scale.push_back(z); point_disp_scale.push_back(scale); // texture mapping tex_coords.push_back(i); } } } // SCENE [GLTFWriter::Scene](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_scene.xhtml) *scene = GLTFWriter::Scene::Create(gltf, "TestScene", "m", 1.0, GLTFWriter::Scene::BT_SOLID, 0.5, 0.5, 0.5); if (!scene) { GLTFWriter::GLTF::Destroy(gltf); throw std::runtime_error("Can't create scene"); } // LIGHTS { // LIGHT NODE [GLTFWriter::Node](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_node.xhtml) *lightNode = GLTFWriter::Node::CreateLight(gltf); if (!lightNode || !scene->[SetLight](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_scene.xhtml#ac92acb916999693ccaaefe8a81962c67)(lightNode)) { GLTFWriter::GLTF::Destroy(gltf); throw std::runtime_error("Can't create light"); } // LIGHTS [GLTFWriter::Light](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_light.xhtml) *light1 = GLTFWriter::Light::CreateAmbient(gltf); lightNode->[AppendLight](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_node.xhtml#a576db36280a02127b5eb662f0566543b)(light1); [GLTFWriter::Light](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_light.xhtml) *light2 = GLTFWriter::Light::CreateDirectional(gltf, 1, 1, 1, -1, -1, -3); lightNode->[AppendLight](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_node.xhtml#a576db36280a02127b5eb662f0566543b)(light2); } // CAMERA { // CAMERA [GLTFWriter::Camera](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_camera.xhtml) *camera = GLTFWriter::Camera::CreateOrthographic(gltf); // CAMERA NODE std::vector<double> mat(16); mat[0] = 1; mat[1] = 0; mat[2] = 0; mat[3] = 0; mat[4] = 0; mat[5] = 1; mat[6] = 0; mat[7] = 0; mat[8] = 0; mat[9] = 0; mat[10] = 1; mat[11] = 0; mat[12] = 0; mat[13] = 0; mat[14] = 0; mat[15] = 1; [GLTFWriter::Node](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_node.xhtml) *cameraNode = GLTFWriter::Node::CreateCamera(gltf, camera, "TestCamera", &mat[0]); scene->[SetCamera](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_scene.xhtml#ae84fba7ea3c00159c2eae7adbfbfa61d)(cameraNode); } // PROXY IMAGE { // Using a PNG file from disk here, but could use in-memory PNG representation as well. [GLTFWriter::Image](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_image.xhtml)* proxy_image = GLTFWriter::Image::Create(gltf, "earth.png", false, true); if (proxy_image) { [GLTFWriter::Node](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_node.xhtml)* proxy_image_node = GLTFWriter::Node::CreateProxyImage(gltf, proxy_image, "scene\_proxy"); if (proxy_image_node) { scene->[SetProxyImage](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_scene.xhtml#a4f02c1b6ff4c656ad44b583a76e95e42)(proxy_image_node); } } } // NODE { [GLTFWriter::Node](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_node.xhtml) *node = GLTFWriter::Node::CreateMesh(gltf, "3D Points"); if (!node || !scene->[AppendMesh](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_scene.xhtml#a76e34d4c05fe34dde0fcc4913ad63981)(node)) { GLTFWriter::GLTF::Destroy(gltf); throw std::runtime_error("Can't create mesh node"); } // MESH [GLTFWriter::Mesh](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_mesh.xhtml) *mesh = GLTFWriter::Mesh::Create(gltf); if (!mesh || !node->[AppendMesh](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_node.xhtml#a68c9eec5fe03405e52b3558a62f8faec)(mesh)) { GLTFWriter::GLTF::Destroy(gltf); throw std::runtime_error("Can't create mesh"); } // TECHNIQUE [GLTFWriter::Technique](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_technique.xhtml) *technique = GLTFWriter::Technique::Create(gltf); if (!technique || // TECHNIQUE STATES !technique->[AppendState](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_technique.xhtml#a8b2b0766157324d5a2093a3fca36379f)(GLTFWriter::State::Create(gltf, GLTFWriter::State::ST_BLENDENABLE, 1)) || !technique->[AppendState](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_technique.xhtml#a8b2b0766157324d5a2093a3fca36379f)(GLTFWriter::State::Create(gltf, GLTFWriter::State::ST_DEPTHTESTENABLE, 1))) { GLTFWriter::GLTF::Destroy(gltf); throw std::runtime_error("Can't create technique"); } // MATERIAL [GLTFWriter::Material](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_material.xhtml) *material = GLTFWriter::Material::Create(gltf, technique); if (!material || // MATERIAL UNIFORM VALUES !material->[AppendValue](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_material.xhtml#a2f8a41e41af7d9b8cd498506f6510dd7)(GLTFWriter::Value::Create(gltf, "texture0", rainbowGradientTexture->GetID()))) { GLTFWriter::GLTF::Destroy(gltf); throw std::runtime_error("Can't create material"); } size\_t numVertices = vertices.size() / 3; // POSITION ATTRIBUTE [GLTFWriter::Attribute](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_attribute.xhtml) *vertex = GLTFWriter::Attribute::CreatePosition(gltf, numVertices, vertices.data()); // TEXCOORD ATTRIBUTE [GLTFWriter::Attribute](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_attribute.xhtml) *texCoord = GLTFWriter::Attribute::CreateTextureCoord(gltf, 0, numVertices, tex_coords.data()); if (!texCoord || !texCoord->[SetMinMax](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_attribute.xhtml#ac7d2ab8c33ae471917966f920524fad1)(GLTFWriter::Attribute::AT_FLOAT, &tex_coord_min, &tex_coord_max)) { GLTFWriter::GLTF::Destroy(gltf); throw std::runtime_error("Can't create textureCoord"); } // DISPLACEMENTSCALE ATTRIBUTE // Specifies the displacement and scaling for each vertex in the proxy geometry // It also triggers "billboard" orientation. [GLTFWriter::Attribute](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_attribute.xhtml) *displacement_scale = GLTFWriter::Attribute::CreateDisplacementScale(gltf, numVertices, point_disp_scale.data()); // INDEX ATTRIBUTE [GLTFWriter::Index](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_index.xhtml)* index = GLTFWriter::Index::Create(gltf, triangles.size(), triangles.data()); // PRIMITIVE [GLTFWriter::Primitive](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_primitive.xhtml) *primitive = GLTFWriter::Primitive::Create(gltf, GLTFWriter::Primitive::PT_TRIANGLES, material, index); if (!primitive || !mesh->[AppendPrimitive](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_mesh.xhtml#afb99ec25e2eebb4390c17f8770e4c23b)(primitive) || !primitive->[AppendAttribute](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_primitive.xhtml#ac4144b4cc35eec9c11b07cc7352d209e)(vertex) || !primitive->[AppendAttribute](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_primitive.xhtml#ac4144b4cc35eec9c11b07cc7352d209e)(texCoord) || !primitive->[AppendAttribute](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_primitive.xhtml#ac4144b4cc35eec9c11b07cc7352d209e)(displacement_scale)) { GLTFWriter::GLTF::Destroy(gltf); throw std::runtime_error("Can't create primitive"); } } if (!gltf->[Write](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_g_l_t_f.xhtml#a0bf3a4ec615dc8810776dd82a65eba91)()) { GLTFWriter::GLTF::Destroy(gltf); throw std::runtime_error("Error creating file"); } [GLTFWriter::GLTF::GLTFError](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_g_l_t_f.xhtml#a5b8141dc8536bc10d1a72996ad6f98b4) error = gltf->[GetError](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_g_l_t_f.xhtml#a63295f8f31619517e94cf27d3a8b9ea8)(); GLTFWriter::GLTF::Destroy(gltf); if (error != GLTFWriter::GLTF::GLTF_ERROR_NONE) throw std::runtime_error("Error creating file"); } [ANSYS::AVZ::GLTFWriter::Attribute](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_attribute.xhtml) Attributes define the per element index values for elements defined by Index. **Definition:** [GLTFAttribute.h:32](_g_l_t_f_attribute_8h_source.xhtml#l00031) [ANSYS::AVZ::GLTFWriter::Attribute::SetMinMax](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_attribute.xhtml#ac7d2ab8c33ae471917966f920524fad1) virtual bool SetMinMax(AttributeType type, const int *mn, const int *mx)=0 [ANSYS::AVZ::GLTFWriter::Camera](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_camera.xhtml) Cameras define an orthographic or perspective projection of the scene. **Definition:** [GLTFCamera.h:28](_g_l_t_f_camera_8h_source.xhtml#l00027) [ANSYS::AVZ::GLTFWriter::GLTF](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_g_l_t_f.xhtml) This is the main class of the GLTFWriter. **Definition:** [GLTFGLTF.h:32](_g_l_t_f_g_l_t_f_8h_source.xhtml#l00031) [ANSYS::AVZ::GLTFWriter::GLTF::Write](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_g_l_t_f.xhtml#a0bf3a4ec615dc8810776dd82a65eba91) virtual bool Write(bool formatJSON=false)=0 [ANSYS::AVZ::GLTFWriter::GLTF::GLTFError](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_g_l_t_f.xhtml#a5b8141dc8536bc10d1a72996ad6f98b4) GLTFError **Definition:** [GLTFGLTF.h:35](_g_l_t_f_g_l_t_f_8h_source.xhtml#l00035) [ANSYS::AVZ::GLTFWriter::GLTF::GetError](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_g_l_t_f.xhtml#a63295f8f31619517e94cf27d3a8b9ea8) virtual GLTFError GetError()=0 [ANSYS::AVZ::GLTFWriter::Image](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_image.xhtml) Images define texture data. **Definition:** [GLTFImage.h:27](_g_l_t_f_image_8h_source.xhtml#l00026) [ANSYS::AVZ::GLTFWriter::Index](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_index.xhtml) Indexes define elements within primitives. **Definition:** [GLTFIndex.h:29](_g_l_t_f_index_8h_source.xhtml#l00028) [ANSYS::AVZ::GLTFWriter::Light](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_light.xhtml) Lights define the light objects that can be added to a light node. **Definition:** [GLTFLight.h:31](_g_l_t_f_light_8h_source.xhtml#l00030) [ANSYS::AVZ::GLTFWriter::Material](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_material.xhtml) Materials describe how primitives are rendered. **Definition:** [GLTFMaterial.h:30](_g_l_t_f_material_8h_source.xhtml#l00029) [ANSYS::AVZ::GLTFWriter::Material::AppendValue](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_material.xhtml#a2f8a41e41af7d9b8cd498506f6510dd7) virtual bool AppendValue(Value *value)=0 [ANSYS::AVZ::GLTFWriter::Mesh](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_mesh.xhtml) Meshes define the renderable objects that can be added to a node. **Definition:** [GLTFMesh.h:104](_g_l_t_f_mesh_8h_source.xhtml#l00103) [ANSYS::AVZ::GLTFWriter::Mesh::AppendPrimitive](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_mesh.xhtml#afb99ec25e2eebb4390c17f8770e4c23b) virtual bool AppendPrimitive(Primitive *primitive)=0 [ANSYS::AVZ::GLTFWriter::Node](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_node.xhtml) Nodes are the GLTFWriter class that contain the data that is defined in the GLTF file. **Definition:** [GLTFNode.h:31](_g_l_t_f_node_8h_source.xhtml#l00030) [ANSYS::AVZ::GLTFWriter::Node::AppendLight](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_node.xhtml#a576db36280a02127b5eb662f0566543b) virtual bool AppendLight(Light *light)=0 [ANSYS::AVZ::GLTFWriter::Node::AppendMesh](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_node.xhtml#a68c9eec5fe03405e52b3558a62f8faec) virtual bool AppendMesh(Mesh *mesh)=0 [ANSYS::AVZ::GLTFWriter::Primitive](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_primitive.xhtml) Primitives are the renderable parts of meshes. **Definition:** [GLTFMesh.h:30](_g_l_t_f_mesh_8h_source.xhtml#l00029) [ANSYS::AVZ::GLTFWriter::Primitive::AppendAttribute](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_primitive.xhtml#ac4144b4cc35eec9c11b07cc7352d209e) virtual bool AppendAttribute(Attribute *attribute)=0 [ANSYS::AVZ::GLTFWriter::Scene](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_scene.xhtml) Scenes are the GLTFWriter class that create the view of the data that is defined in the GLTF file. **Definition:** [GLTFScene.h:29](_g_l_t_f_scene_8h_source.xhtml#l00028) [ANSYS::AVZ::GLTFWriter::Scene::SetProxyImage](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_scene.xhtml#a4f02c1b6ff4c656ad44b583a76e95e42) virtual bool SetProxyImage(Node *image)=0 [ANSYS::AVZ::GLTFWriter::Scene::AppendMesh](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_scene.xhtml#a76e34d4c05fe34dde0fcc4913ad63981) virtual bool AppendMesh(Node *mesh)=0 [ANSYS::AVZ::GLTFWriter::Scene::SetLight](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_scene.xhtml#ac92acb916999693ccaaefe8a81962c67) virtual bool SetLight(Node *light)=0 [ANSYS::AVZ::GLTFWriter::Scene::SetCamera](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_scene.xhtml#ae84fba7ea3c00159c2eae7adbfbfa61d) virtual bool SetCamera(Node *camera)=0 [ANSYS::AVZ::GLTFWriter::Technique](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_technique.xhtml) Techniques performs the rendering of primitives. **Definition:** [GLTFTechnique.h:240](_g_l_t_f_technique_8h_source.xhtml#l00239) [ANSYS::AVZ::GLTFWriter::Technique::AppendState](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_technique.xhtml#a8b2b0766157324d5a2093a3fca36379f) virtual bool AppendState(State *state)=0 [ANSYS::AVZ::GLTFWriter::Texture](class_a_n_s_y_s_1_1_a_v_z_1_1_g_l_t_f_writer_1_1_texture.xhtml) Textures are images that can be used to color a primitive. **Definition:** [GLTFTexture.h:28](_g_l_t_f_texture_8h_source.xhtml#l00027)