Add samplerLinearClamp preset (linear filter, clamp-to-edge, no mipmaps)

Ideal for UI elements, sprites, and render targets. Renderer.c in ObjectivelyMVC
uses exactly this sampler configuration.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: jdolan

Sources/ObjectivelyGPU/RenderDevice.c

@@ -47,6 +47,7 @@ static void dealloc(Object *self) {
   if (this->device) {
     SDL_ReleaseGPUSampler(this->device, this->_samplerNearest);
     SDL_ReleaseGPUSampler(this->device, this->_samplerLinear);
+    SDL_ReleaseGPUSampler(this->device, this->_samplerLinearClamp);
     SDL_ReleaseGPUSampler(this->device, this->_samplerAnisotropic);
   }
 
@@ -237,6 +238,27 @@ static SDL_GPUSampler *samplerLinear(const RenderDevice *self) {
   return this->_samplerLinear;
 }
 
+/**
+ * @fn SDL_GPUSampler *RenderDevice::samplerLinearClamp(const RenderDevice *self)
+ * @memberof RenderDevice
+ */
+static SDL_GPUSampler *samplerLinearClamp(const RenderDevice *self) {
+  assert(self);
+
+  RenderDevice *this = (RenderDevice *) self;
+  if (!this->_samplerLinearClamp) {
+    this->_samplerLinearClamp = $(self, createSampler, &(SDL_GPUSamplerCreateInfo) {
+      .min_filter = SDL_GPU_FILTER_LINEAR,
+      .mag_filter = SDL_GPU_FILTER_LINEAR,
+      .mipmap_mode = SDL_GPU_SAMPLERMIPMAPMODE_NEAREST,
+      .address_mode_u = SDL_GPU_SAMPLERADDRESSMODE_CLAMP_TO_EDGE,
+      .address_mode_v = SDL_GPU_SAMPLERADDRESSMODE_CLAMP_TO_EDGE,
+      .address_mode_w = SDL_GPU_SAMPLERADDRESSMODE_CLAMP_TO_EDGE,
+    });
+  }
+  return this->_samplerLinearClamp;
+}
+
 /**
  * @fn SDL_GPUSampler *RenderDevice::samplerNearest(const RenderDevice *self)
  * @memberof RenderDevice
@@ -794,6 +816,7 @@ static void initialize(Class *clazz) {
   ((RenderDeviceInterface *) clazz->interface)->releaseTransferBuffer = releaseTransferBuffer;
   ((RenderDeviceInterface *) clazz->interface)->samplerAnisotropic = samplerAnisotropic;
   ((RenderDeviceInterface *) clazz->interface)->samplerLinear = samplerLinear;
+  ((RenderDeviceInterface *) clazz->interface)->samplerLinearClamp = samplerLinearClamp;
   ((RenderDeviceInterface *) clazz->interface)->samplerNearest = samplerNearest;
   ((RenderDeviceInterface *) clazz->interface)->setAllowedFramesInFlight = setAllowedFramesInFlight;
   ((RenderDeviceInterface *) clazz->interface)->setBufferName = setBufferName;

Sources/ObjectivelyGPU/RenderDevice.h

@@ -105,6 +105,12 @@ struct RenderDevice {
    */
   SDL_GPUSampler *_samplerLinear;
 
+  /**
+   * @brief Cached bilinear clamp-to-edge sampler, initialized on first use.
+   * @private
+   */
+  SDL_GPUSampler *_samplerLinearClamp;
+
   /**
    * @brief Cached anisotropic sampler, initialized on first use.
    * @private
@@ -240,6 +246,19 @@ struct RenderDeviceInterface {
    */
   SDL_GPUSampler *(*samplerLinear)(const RenderDevice *self);
 
+  /**
+   * @fn SDL_GPUSampler *RenderDevice::samplerLinearClamp(const RenderDevice *self)
+   * @brief Returns a cached bilinear sampler with clamp-to-edge addressing (no mipmaps).
+   * @details The sampler is created on first call and reused thereafter. It is
+   *   released automatically in `dealloc`. Do not release it manually.
+   *   This is the correct sampler for UI elements, sprites, and render targets —
+   *   linear magnification without edge bleeding or mip artifacts.
+   * @param self The RenderDevice.
+   * @return A cached `SDL_GPUSampler` suitable for UI and sprite rendering.
+   * @memberof RenderDevice
+   */
+  SDL_GPUSampler *(*samplerLinearClamp)(const RenderDevice *self);
+
   /**
    * @fn SDL_GPUSampler *RenderDevice::samplerNearest(const RenderDevice *self)
    * @brief Returns a cached nearest-neighbor sampler (clamp-to-edge address).