Question on rendering!

[capslocknanda]

Thank you for sharing this awesome work.
I am rendering this figure using gl4 and GLFW and glad,

and here is my main loop to render this:
int main()
{
// glfw: initialize and configure
// ------------------------------
glfwInit();
if (!glfwInit())
{
// Handle initialization error
std::cout << "Failed to initialize GLFW" << std::endl;
}

glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

#ifdef APPLE
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif

// glfw window creation
// --------------------
GLFWwindow *window = glfwCreateWindow(800, 600, "drawing lines", NULL, NULL);
// glfwSetWindowAttrib(window, GLFW_MAXIMIZED, GLFW_TRUE);
if (!window)
{
    std::cout << "Failed to create GLFW window" << std::endl;
    glfwTerminate();
    return -1;
}
glfwMakeContextCurrent(window);

// glad: load all OpenGL function pointers
// ---------------------------------------

if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
    std::cout << "Failed to initialize GLAD" << std::endl;
    return -1;
}

camera.position = glm::vec3(3, 3, 3);

// 3d lines example
Line line1(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(1.0f, 0.0f, 0.0f));
line1.setColor(glm::vec3(1.0f, 0.0f, 0.0f));
Line line2(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0));
line2.setColor(glm::vec3(0.0f, 1.0f, 0.0f));
Line line3(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 0.0f, 1.0f));
line3.setColor(glm::vec3(0.0f, 0.0f, 1.0f));

std::vector<std::vector<int>> edgesList{{0, 1}, {1, 2}, {1, 5}, {2, 3}, {3, 4}, {5, 6}, {6, 7}, {1, 8}, {1, 9}};

glm::mat4 projection = glm::perspective(glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);

float angle = 0.0f;
float rotationSpeed = 50.0f;

std::vector<std::vector<double>> examplePose{
    {0.564655185, 0},            // head
    {0.512931049, 0.25469169},   // neck
    {0.0517241396, 0.209115282}, // left hip
    {0, 0.648793578},            // right hip
    {0.637931049, 0.705093801},  // left shoulder
    {1, 0.276139408},            // left elbow
    {0.883620679, 0.675603211},  // left wrist
    {0.232758626, 0.571045578},  // right shoulder
    {0.198275864, 0.975871325},  // right elbow
    {0.711206913, 1},            // right wrist
};

// render loop
// -----------
while (!glfwWindowShouldClose(window))
{
    float currentFrame = glfwGetTime();
    deltaTime = currentFrame - lastFrame;
    // input
    // -----
    processInput(window);

    // render
    // ------
    glClearColor(0.0, 0.0, 0.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);

    // angle = deltaTime * rotationSpeed;

    // update camera position (rotating)
    // camera.position = glm::vec3(3 * cos(glm::radians(angle)), 3, 3 * sin(glm::radians(angle)));
    glm::mat4 view = lookAt(camera.position, glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));

    for (auto &edge : edgesList)
    {
        int v1 = edge[0];
        int v2 = edge[1];
        Line lineN(glm::vec3(-examplePose[v1][0], -examplePose[v1][1], 0),
                   glm::vec3(-examplePose[v2][0], -examplePose[v2][1], 0));
        lineN.setColor(glm::vec3(1, 0, 0));
        lineN.setMVP(projection * view);
        lineN.draw();
    }

    line1.setMVP(projection * view);
    line2.setMVP(projection * view);
    line3.setMVP(projection * view);

    line1.draw();
    line2.draw();
    line3.draw();

    // line4.draw();

    // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
    // -------------------------------------------------------------------------------
    glfwSwapBuffers(window);
    glfwPollEvents();
}

// glfw: terminate, clearing all previously allocated GLFW resources.
// ------------------------------------------------------------------
glfwTerminate();
return 0;

}

How can I render the same in a sub-window in another of my program which uses Imgui with SDL and opengl,
I am currently doing this :

void render3DPose(cv::Mat &PoseKeypoint, std::vector<std::vector> edgesList, GLuint rbo,
GLuint framebuffer, GLuint texture) {
ImGui::Begin("Rendering 3D Pose");
ImGui::SetWindowPos(ImVec2(380, 140));
ImVec2 windowSize = ImVec2(450, 550);
ImVec2 size = ImVec2(ImGui::GetWindowWidth(), ImGui::GetWindowHeight());
ImGui::SetWindowSize("Rendering 3D Pose", windowSize);

glViewport(0, 0, (int)windowSize.x, (int)windowSize.y);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glClearColor(0.2f, 0.3f, 0.4f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

float angle = 40.0f;
Camera camera;
camera.position = glm::vec3(3.0f, 3.0f, 3.0f);
glm::mat4 projection =
    glm::perspective(glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);

glm::mat4 view =
    glm::lookAt(camera.position, glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));

cv::Mat PoseKeypoint3dmat = PoseKeypoint.clone();
//// Normalize keypoint coordinates to 0-1 range
cv::normalize(PoseKeypoint3dmat.col(0), PoseKeypoint3dmat.col(0), 0.0, 1.0, cv::NORM_MINMAX);
cv::normalize(PoseKeypoint3dmat.col(1), PoseKeypoint3dmat.col(1), 0.0, 1.0, cv::NORM_MINMAX);

for (auto &edge : edgesList) {
    int v1 = edge[0];
    int v2 = edge[1];
    Line lineN(
        glm::vec3(PoseKeypoint3dmat.at<float>(v1, 0), -PoseKeypoint3dmat.at<float>(v1, 1), 0),
        glm::vec3(PoseKeypoint3dmat.at<float>(v2, 0), -PoseKeypoint3dmat.at<float>(v2, 1), 0));
    lineN.setColor(glm::vec3(1, 0, 0));
    lineN.setMVP(projection * view);
    lineN.draw();
}

Line line1(glm::vec3(0, 0, 0), glm::vec3(1, 0, 0));
line1.setColor(glm::vec3(1, 0, 0));
Line line2(glm::vec3(0, 0, 0), glm::vec3(0, 1, 0));
line2.setColor(glm::vec3(0, 1, 0));
Line line3(glm::vec3(0, 0, 0), glm::vec3(0, 0, 1));
line3.setColor(glm::vec3(0, 0, 1));

line1.setMVP(projection * view);
line2.setMVP(projection * view);
line3.setMVP(projection * view);

line1.draw();
line2.draw();
line3.draw();

glBindFramebuffer(GL_FRAMEBUFFER, 0);

// Clear the screen
glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

ImTextureID tex_id = (void *)(intptr_t)texture;
ImGui::Image(tex_id, windowSize, ImVec2(0, 1), ImVec2(1, 0));

ImGui::End();

}
I am using the same glm camera parameters, but ending up getting this:

Any help will be appreciated. Thank you!

[ocornut]

I am sorry but nothing in your question is specific to dear imgui, this is the wrong forum to ask this.

[capslocknanda]

I did convert it to a ImTextureID. My question is is there any way to render another sdl window in side ImGui subwindow?
Thank you!

[ocornut]

No, you can render a texture meaning you have to render-to-texture using opengl to do this, as you did. Your problem seems to be a 3d/projection transform problem.