multi_render_blender/src/main/BlenderProcess.js

const { spawn } = require("child_process");
const PathResolver = require("./PathResolver.js");

const BlenderProcess = {
    render_frame: (obj_params) => {
        let str_blend_path = obj_params.str_blend_path;
        let str_camera_name = obj_params.str_camera_name;
        let nb_frame = obj_params.nb_frame;
        let nb_resolution_x = obj_params.nb_resolution_x;
        let nb_resolution_y = obj_params.nb_resolution_y;
        let str_format = obj_params.str_format;
        let str_output_path = obj_params.str_output_path;

        let str_safe_name = str_camera_name.replace(/\\/g, "\\\\").replace(/'/g, "\\'");

        let list_python_lines = [
            "import bpy",
            "scene=bpy.context.scene",
            "scene.camera=bpy.data.objects['" + str_safe_name + "']",
            "scene.render.resolution_x=" + nb_resolution_x,
            "scene.render.resolution_y=" + nb_resolution_y,
        ];

        if (obj_params.obj_render_settings) {
            let obj_rs = obj_params.obj_render_settings;
            if (obj_rs.str_engine) {
                list_python_lines.push("scene.render.engine='" + obj_rs.str_engine + "'");
            }
            if (obj_rs.nb_resolution_percentage !== undefined) {
                list_python_lines.push("scene.render.resolution_percentage=" + obj_rs.nb_resolution_percentage);
            }
            if (obj_rs.is_film_transparent !== undefined) {
                list_python_lines.push("scene.render.film_transparent=" + (obj_rs.is_film_transparent ? "True" : "False"));
            }
            if (obj_rs.str_engine === "CYCLES") {
                if (obj_rs.nb_samples !== undefined) {
                    list_python_lines.push("scene.cycles.samples=" + obj_rs.nb_samples);
                }
                if (obj_rs.str_device) {
                    list_python_lines.push("scene.cycles.device='" + obj_rs.str_device + "'");
                }
                if (obj_rs.is_denoise !== undefined) {
                    list_python_lines.push("scene.cycles.use_denoising=" + (obj_rs.is_denoise ? "True" : "False"));
                }
            } else if (obj_rs.str_engine === "BLENDER_EEVEE" || obj_rs.str_engine === "BLENDER_EEVEE_NEXT") {
                if (obj_rs.nb_samples !== undefined) {
                    list_python_lines.push("try:\n scene.eevee.taa_render_samples=" + obj_rs.nb_samples + "\nexcept:\n try:\n  scene.eevee.samples=" + obj_rs.nb_samples + "\n except:pass");
                }
            }
        }

        let str_python_expr = list_python_lines.join(";");

        if (obj_params.list_collections && obj_params.list_collections.length > 0) {
            str_python_expr += "\ndef _slc(lc,n,v):"
                + "\n for c in lc.children:"
                + "\n  if c.name==n:c.exclude=v;return"
                + "\n  _slc(c,n,v)\n";
            for (let obj_col of obj_params.list_collections) {
                let str_col_safe = obj_col.str_name.replace(/\\/g, "\\\\").replace(/'/g, "\\'");
                let str_val = obj_col.is_hide_render ? "True" : "False";
                str_python_expr += "bpy.data.collections['" + str_col_safe + "'].hide_render=" + str_val
                    + ";_slc(bpy.context.view_layer.layer_collection,'" + str_col_safe + "'," + str_val + ")\n";
            }
        }

        let list_args = [
            "-b", str_blend_path,
            "--python-expr", str_python_expr,
            "-o", str_output_path,
            "-F", str_format,
            "-f", String(nb_frame),
        ];

        return new Promise((resolve, reject) => {
            let str_stdout = "";
            let str_stderr = "";

            let obj_process = spawn(PathResolver.get_blender_path(), list_args);

            obj_process.stdout.on("data", (obj_data) => {
                str_stdout += obj_data.toString();
                if (obj_params.fn_on_stdout) {
                    obj_params.fn_on_stdout(obj_data.toString());
                }
            });

            obj_process.stderr.on("data", (obj_data) => {
                str_stderr += obj_data.toString();
            });

            obj_process.on("close", (nb_code) => {
                if (nb_code !== 0) {
                    reject({
                        str_message: "Blender a quitte avec le code " + nb_code,
                        str_stderr: str_stderr,
                        str_stdout: str_stdout,
                    });
                    return;
                }

                let str_rendered_file = BlenderProcess._find_rendered_file(str_stdout);
                resolve({
                    str_rendered_file: str_rendered_file,
                    str_stdout: str_stdout,
                });
            });

            obj_process.on("error", (obj_err) => {
                reject({
                    str_message: "Impossible de lancer Blender : " + obj_err.message,
                    str_stderr: "",
                    str_stdout: "",
                });
            });

            // Store process reference for kill support
            if (obj_params.fn_on_process) {
                obj_params.fn_on_process(obj_process);
            }
        });
    },

    _find_rendered_file: (str_stdout) => {
        let list_lines = str_stdout.split("\n");
        for (let str_line of list_lines) {
            let nb_index = str_line.indexOf("Saved: ");
            if (nb_index !== -1) {
                let str_path = str_line.substring(nb_index + 7).trim();
                // Remove trailing info like " Time: 00:01.23"
                let nb_time_index = str_path.indexOf(" Time:");
                if (nb_time_index !== -1) {
                    str_path = str_path.substring(0, nb_time_index).trim();
                }
                // Blender 5.x wraps path in single quotes: Saved: '/path/file.png'
                if (str_path.startsWith("'") && str_path.endsWith("'")) {
                    str_path = str_path.substring(1, str_path.length - 1);
                }
                return str_path;
            }
        }
        return null;
    },
};

module.exports = BlenderProcess;