From 4e7b2f21249086e5d5d5f7ead7c36a7ccd093688 Mon Sep 17 00:00:00 2001
From: Haroon Qureshi <haroonq@google.com>
Date: Wed, 29 Apr 2026 09:12:58 -0700
Subject: [PATCH] Allow dimensions to be specified when creating a render
 target.

PiperOrigin-RevId: 907622395
Change-Id: I0f806f4d77afa6a178a20d36dae3e96b81359494
---
 .../filament/compat/mjr_filament_renderer.cc          |  3 ++-
 src/experimental/filament/filament/render_target.cc   | 11 ++++++++++-
 src/experimental/filament/render_context_filament.cc  |  1 +
 src/experimental/filament/render_context_filament.h   |  6 ++++++
 4 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/experimental/filament/compat/mjr_filament_renderer.cc b/src/experimental/filament/compat/mjr_filament_renderer.cc
index c7f74ecf..fcd8f31e 100644
--- a/src/experimental/filament/compat/mjr_filament_renderer.cc
+++ b/src/experimental/filament/compat/mjr_filament_renderer.cc
@@ -134,11 +134,12 @@ void MjrFilamentRenderer::ReadPixels(mjrRect viewport, unsigned char* rgb,
   if (rgb) {
     mjrRenderTargetConfig config;
     mjr_defaultRenderTargetConfig(&config);
+    config.width = viewport.width;
+    config.height = viewport.height;
     config.color_format = mjPIXEL_FORMAT_RGB8;
     config.depth_format = mjPIXEL_FORMAT_DEPTH32F;
     auto target =
         std::make_unique<RenderTarget>(filament_context_.get(), config);
-    target->Prepare(viewport.width, viewport.height);
     render_requests_[0].target = target.get();
     render_requests_[1].target = target.get();
 
diff --git a/src/experimental/filament/filament/render_target.cc b/src/experimental/filament/filament/render_target.cc
index 8b6afb3e..d8919a96 100644
--- a/src/experimental/filament/filament/render_target.cc
+++ b/src/experimental/filament/filament/render_target.cc
@@ -34,7 +34,11 @@ namespace mujoco {
 
 RenderTarget::RenderTarget(FilamentContext* ctx,
                            const mjrRenderTargetConfig& config)
-    : ctx_(ctx), config_(config) {}
+    : ctx_(ctx), config_(config) {
+  if (config_.width > 0 && config_.height > 0) {
+    Prepare(config_.width, config_.height);
+  }
+}
 
 RenderTarget::~RenderTarget() noexcept {
   Destroy();
@@ -47,6 +51,11 @@ void RenderTarget::Prepare(int width, int height) {
   Destroy();
   width_ = width;
   height_ = height;
+  if (width_ <= 0 || height_ <= 0) {
+    width_ = 0;
+    height_ = 0;
+    return;
+  }
 
   mjrTextureConfig color_config;
   mjr_defaultTextureConfig(&color_config);
diff --git a/src/experimental/filament/render_context_filament.cc b/src/experimental/filament/render_context_filament.cc
index 74c1d3e1..322118a1 100644
--- a/src/experimental/filament/render_context_filament.cc
+++ b/src/experimental/filament/render_context_filament.cc
@@ -116,6 +116,7 @@ void mjr_defaultRenderableParams(mjrRenderableParams* params) {
 }
 
 void mjr_defaultRenderTargetConfig(mjrRenderTargetConfig* config) {
+  memset(config, 0, sizeof(mjrRenderTargetConfig));
   config->color_format = mjPIXEL_FORMAT_RGBA8;
   config->depth_format = mjPIXEL_FORMAT_DEPTH32F;
 }
diff --git a/src/experimental/filament/render_context_filament.h b/src/experimental/filament/render_context_filament.h
index 577b11a6..0f5ee16a 100644
--- a/src/experimental/filament/render_context_filament.h
+++ b/src/experimental/filament/render_context_filament.h
@@ -326,7 +326,13 @@ void mjr_defaultLightParams(mjrLightParams* params);
 
 // Defines the basic properties of a render target.
 struct mjrRenderTargetConfig {
+  // The width of the render target.
+  int width;
+  // The height of the render target.
+  int height;
+  // The format of the color buffer in the render target.
   mjrPixelFormat color_format;
+  // The format of the depth buffer in the render target.
   mjrPixelFormat depth_format;
 };