From a3425c72a75acd7f1655881ecbf09a99ba4d4f29 Mon Sep 17 00:00:00 2001
From: Yuval Tassa <tassa@google.com>
Date: Thu, 30 Jul 2026 13:13:07 -0700
Subject: [PATCH] Ignore unsupported light types in the classic renderer.

The classic renderer supports only directional and spot lights, but initLights() set GL light colors for every scene light before dispatching on type, and the render passes enabled GL light slots without filtering. Since no position was ever set for unsupported types (mjLIGHT_POINT, mjLIGHT_IMAGE), OpenGL's default eye-space position turned them into phantom headlights with the model light's diffuse color, washing out the scene. A cast-shadow image light additionally triggered a full shadow pass with an unset light projection.

Filter all light setup and enable sites on a shared type predicate, so unsupported light types contribute nothing. The no-lights ambient fallback now applies when no supported lights are present.

PiperOrigin-RevId: 956696548
Change-Id: Ic29763df7f9330f21d94f14501ae2559fd460f2b
---
 src/render/classic/render_gl3.c | 53 +++++++++++++++++++++++----------
 1 file changed, 37 insertions(+), 16 deletions(-)

diff --git a/src/render/classic/render_gl3.c b/src/render/classic/render_gl3.c
index f986c0ff..b5ee76c3 100644
--- a/src/render/classic/render_gl3.c
+++ b/src/render/classic/render_gl3.c
@@ -667,10 +667,23 @@ static void initGL3(const mjvScene* scn, const mjrContext* con) {
 
 
 
+// light type is supported by the fixed-function pipeline
+static int isSupportedLight(const mjvLight* light) {
+  return light->type == mjLIGHT_DIRECTIONAL || light->type == mjLIGHT_SPOT;
+}
+
+
+
 // init lights
 static void initLights(mjvScene* scn) {
-  // create some ambient light if no ligths are present
-  float global = scn->nlight ? 0 : 0.3f;
+  // count supported lights
+  int nsupported = 0;
+  for (int i=0; i < scn->nlight; i++) {
+    nsupported += isSupportedLight(scn->lights+i);
+  }
+
+  // create some ambient light if no supported lights are present
+  float global = nsupported ? 0 : 0.3f;
   float rgba_global[4] = {global, global, global, 1};
 
   // init light model
@@ -680,6 +693,11 @@ static void initLights(mjvScene* scn) {
 
   // set light properties
   for (int i=0; i < scn->nlight; i++) {
+    // ignore unsupported light types: mjLIGHT_POINT, mjLIGHT_IMAGE
+    if (!isSupportedLight(scn->lights+i)) {
+      continue;
+    }
+
     // colors
     glLightfv(GL_LIGHT0+i, GL_AMBIENT, scn->lights[i].ambient);
     glLightfv(GL_LIGHT0+i, GL_DIFFUSE, scn->lights[i].diffuse);
@@ -702,10 +720,6 @@ static void initLights(mjvScene* scn) {
       glLightf(GL_LIGHT0+i, GL_LINEAR_ATTENUATION,    scn->lights[i].attenuation[1]);
       glLightf(GL_LIGHT0+i, GL_QUADRATIC_ATTENUATION, scn->lights[i].attenuation[2]);
     }
-
-    else {
-      // ignore unsupported light types: mjLIGHT_POINT, mjLIGHT_IMAGE
-    }
   }
 
   // disable all lights (enable selectively in render)
@@ -1089,10 +1103,12 @@ void mjr_render(mjrRect viewport, mjvScene* scn, const mjrContext* con) {
           glPushMatrix();
           mjr_reflect(thisgeom->pos, thisgeom->mat);
 
-          // set light position and direction, enable
+          // set light position and direction, enable supported lights
           for (int j=0; j < nlight; j++) {
-            adjustLight(scn->lights+j, j);
-            glEnable(GL_LIGHT0+j);
+            if (isSupportedLight(scn->lights+j)) {
+              adjustLight(scn->lights+j, j);
+              glEnable(GL_LIGHT0+j);
+            }
           }
 
           // render reflected non-transparent geoms, except for thisgeom
@@ -1143,8 +1159,13 @@ void mjr_render(mjrRect viewport, mjvScene* scn, const mjrContext* con) {
 
     // set light position and direction, enable non-shadow lights
     for (int i=0; i < nlight; i++) {
-      // set light
+      // get pointer, ignore unsupported light types
       thislight = scn->lights + i;
+      if (!isSupportedLight(thislight)) {
+        continue;
+      }
+
+      // set light
       adjustLight(thislight, i);
 
       // enable lights without shadows
@@ -1184,10 +1205,10 @@ void mjr_render(mjrRect viewport, mjvScene* scn, const mjrContext* con) {
     // shadow map rendering
     if (scn->flags[mjRND_SHADOW] && con->shadowFBO) {
       for (int i=0; i < nlight; i++) {
-        // get pointer
+        // get pointer, ignore unsupported light types
         thislight = scn->lights + i;
 
-        if (thislight->castshadow) {
+        if (thislight->castshadow && isSupportedLight(thislight)) {
           // prepare up-direction
           mjr_orthoVec(temp, thislight->dir);
 
@@ -1210,8 +1231,6 @@ void mjr_render(mjrRect viewport, mjvScene* scn, const mjrContext* con) {
           } else if (thislight->type == mjLIGHT_SPOT) {
             mjr_perspective(mju_min(2*thislight->cutoff*con->shadowScale, 160), 1,
                             cam.frustum_near, cam.frustum_far);
-          } else {
-            // ignore unsupported light types: mjLIGHT_POINT, mjLIGHT_IMAGE
           }
           glGetFloatv(GL_PROJECTION_MATRIX, lightProject);
 
@@ -1408,9 +1427,11 @@ void mjr_render(mjrRect viewport, mjvScene* scn, const mjrContext* con) {
 
     //------------------------------------ transparent regular rendering
 
-    // enable lights
+    // enable supported lights
     for (int i=0; i < nlight; i++) {
-      glEnable(GL_LIGHT0+i);
+      if (isSupportedLight(scn->lights+i)) {
+        glEnable(GL_LIGHT0+i);
+      }
     }
 
     // blend mode