Added SDL_SCALEMODE_PIXELART

This is based on the algorithm presented by t3ssel8r:
https://www.youtube.com/watch?v=d6tp43wZqps

Author: slouken

include/SDL3/SDL_surface.h

@@ -83,8 +83,9 @@ typedef Uint32 SDL_SurfaceFlags;
 typedef enum SDL_ScaleMode
 {
     SDL_SCALEMODE_INVALID = -1,
-    SDL_SCALEMODE_NEAREST, /**< nearest pixel sampling */
-    SDL_SCALEMODE_LINEAR   /**< linear filtering */
+    SDL_SCALEMODE_NEAREST,  /**< nearest pixel sampling */
+    SDL_SCALEMODE_LINEAR,   /**< linear filtering */
+    SDL_SCALEMODE_PIXELART  /**< nearest pixel sampling with improved scaling for pixel art */
 } SDL_ScaleMode;
 
 /**

src/render/SDL_render.c

@@ -1964,8 +1964,12 @@ bool SDL_SetTextureScaleMode(SDL_Texture *texture, SDL_ScaleMode scaleMode)
 {
     CHECK_TEXTURE_MAGIC(texture, false);
 
-    if (scaleMode != SDL_SCALEMODE_NEAREST &&
-        scaleMode != SDL_SCALEMODE_LINEAR) {
+    switch (scaleMode) {
+    case SDL_SCALEMODE_NEAREST:
+    case SDL_SCALEMODE_LINEAR:
+    case SDL_SCALEMODE_PIXELART:
+        break;
+    default:
         return SDL_InvalidParamError("scaleMode");
     }
 
@@ -5707,7 +5711,7 @@ static bool CreateDebugTextAtlas(SDL_Renderer *renderer)
     // Convert temp surface into texture
     SDL_Texture *texture = SDL_CreateTextureFromSurface(renderer, atlas);
     if (texture) {
-        SDL_SetTextureScaleMode(texture, SDL_SCALEMODE_NEAREST);
+        SDL_SetTextureScaleMode(texture, SDL_SCALEMODE_PIXELART);
         renderer->debug_char_texture_atlas = texture;
     }
     SDL_DestroySurface(atlas);

src/render/direct3d/SDL_render_d3d.c

@@ -921,6 +921,7 @@ static void UpdateTextureScaleMode(D3D_RenderData *data, SDL_ScaleMode scaleMode
 {
     if (scaleMode != data->scaleMode[index]) {
         switch (scaleMode) {
+        case SDL_SCALEMODE_PIXELART:
         case SDL_SCALEMODE_NEAREST:
             IDirect3DDevice9_SetSamplerState(data->device, index, D3DSAMP_MINFILTER, D3DTEXF_POINT);
             IDirect3DDevice9_SetSamplerState(data->device, index, D3DSAMP_MAGFILTER, D3DTEXF_POINT);