use PBO for timelapse data read

src/canvas_layer.cpp

@@ -101,6 +101,49 @@ Texture2D Layer::gen_equirect(glm::ivec2 size /*= { 0, 0 }*/)
     return ret;
 }
 
+PBO Layer::gen_equirect_pbo(glm::ivec2 size /*= { 0, 0 }*/)
+{
+    PBO pbo;
+    App::I->render_task([&]
+        {
+            gl_state gl;
+            gl.save();
+
+            TextureCube cube;
+            RTT latlong;
+
+            if (size.x == 0 || size.y == 0)
+                size = { w, h };
+
+            cube = gen_cube();
+            latlong.create(size.x * 4, size.y * 2);
+
+            glDisable(GL_BLEND);
+
+            latlong.bindFramebuffer();
+            latlong.clear({ 0, 1, 1, 1 });
+            glViewport(0, 0, latlong.getWidth(), latlong.getHeight());
+            glActiveTexture(GL_TEXTURE0);
+            glBindTexture(GL_TEXTURE_CUBE_MAP, cube.m_cubetex_id);
+
+            ShaderManager::use(kShader::Equirect);
+            ShaderManager::u_mat4(kShaderUniform::MVP, glm::ortho(-.5f, .5f, -.5f, .5f, -1.f, 1.f));
+            ShaderManager::u_int(kShaderUniform::Tex, 0);
+            Canvas::I->m_sampler.bind(0);
+            Canvas::I->m_plane.draw_fill();
+
+            latlong.unbindFramebuffer();
+
+            pbo.create(latlong);
+
+            latlong.destroy();
+            cube.destroy();
+
+            gl.restore();
+        });
+    return pbo;
+}
+
 void Layer::destroy()
 {
     for (int i = 0; i < 6; i++)