GPU: Add enable_depth_clip to RasterizerState (#10964)

include/SDL3/SDL_gpu.h

@@ -1355,6 +1355,11 @@ typedef struct SDL_GPUTransferBufferCreateInfo
  * A structure specifying the parameters of the graphics pipeline rasterizer
  * state.
  *
+ * NOTE: Some backend APIs (D3D11/12) will enable depth clamping even if
+ * enable_depth_clip is true. If you rely on this clamp+clip behavior,
+ * consider enabling depth clip and then manually clamping depth in your
+ * fragment shaders on Metal and Vulkan.
+ *
  * \since This struct is available since SDL 3.0.0
  *
  * \sa SDL_GPUGraphicsPipelineCreateInfo
@@ -1368,9 +1373,9 @@ typedef struct SDL_GPURasterizerState
     float depth_bias_clamp;            /**< The maximum depth bias of a fragment. */
     float depth_bias_slope_factor;     /**< A scalar factor applied to a fragment's slope in depth calculations. */
     bool enable_depth_bias;        /**< true to bias fragment depth values. */
+    bool enable_depth_clip;        /**< true to enable depth clip, false to enable depth clamp. */
     Uint8 padding1;
     Uint8 padding2;
-    Uint8 padding3;
 } SDL_GPURasterizerState;
 
 /**