fix(gl): detach unused FBO attachments in _sg_gl_begin_pass

The GL backend uses a single shared FBO for all offscreen passes.
When switching from a pass with depth-stencil to one without,
the old depth-stencil attachment remained bound, causing rendering
to be clipped to the smaller attachment's dimensions.

This fix explicitly detaches:
- Unused color attachment slots (beyond num_color_views)
- Depth-stencil attachment when not used in the current pass

Fixes rendering clipping when mixing render targets with and
without depth-stencil attachments in the same frame.

Reproduction: https://github.com/etherbound-dev/sokol-depth-stencil-bug

1 files changed, 8 insertions, 0 deletions

diff --git a/sokol_gfx.h b/sokol_gfx.h
index 11d387e2..1d08c14e 100644
--- a/sokol_gfx.h
+++ b/sokol_gfx.h
@@ -10909,6 +10909,11 @@ _SOKOL_PRIVATE void _sg_gl_begin_pass(const sg_pass* pass, const _sg_attachments
                 _sg_gl_fb_attach_texture(view, gl_att_type);
             }
         }
+        // explicitly detach unused color attachments
+        for (int i = atts->num_color_views; i < SG_MAX_COLOR_ATTACHMENTS; i++) {
+            const GLenum gl_att_type = (GLenum)(GL_COLOR_ATTACHMENT0 + i);
+            glFramebufferTexture2D(GL_FRAMEBUFFER, gl_att_type, GL_TEXTURE_2D, 0, 0);
+        }
         if (atts->ds_view) {
             const _sg_view_t* view = atts->ds_view;
             const _sg_image_t* img = _sg_image_ref_ptr(&view->cmn.img.ref);
@@ -10918,6 +10923,9 @@ _SOKOL_PRIVATE void _sg_gl_begin_pass(const sg_pass* pass, const _sg_attachments
             } else {
                 _sg_gl_fb_attach_texture(view, gl_att_type);
             }
+        } else {
+            // explicitly detach depth-stencil attachment if not used in this pass
+            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_TEXTURE_2D, 0, 0);
         }
         if (!_sg_gl_check_framebuffer_status()) {
             _sg.cur_pass.valid = false;