filters: rename pl_filter_triangle/box to bilinear/nearest

I have no idea why I ever gave these such confusing names. Just rename
them and keep around the old names for backwards compatibility.

API bump because this is technically an ABI break (symbol rename).

meson.build

@@ -2,7 +2,7 @@ project('libplacebo', ['c', 'cpp'],
   license: 'LGPL2.1+',
   default_options: ['c_std=c99', 'cpp_std=c++11', 'warning_level=2'],
   meson_version: '>=0.51',
-  version: '3.116.0',
+  version: '3.117.0',
 )
 
 # Version number

src/filters.c

@@ -532,11 +532,11 @@ const struct pl_filter_config pl_filter_spline64 = {
     .kernel = &pl_filter_function_spline64,
 };
 
-const struct pl_filter_config pl_filter_box = {
+const struct pl_filter_config pl_filter_nearest = {
     .kernel = &pl_filter_function_box,
 };
 
-const struct pl_filter_config pl_filter_triangle = {
+const struct pl_filter_config pl_filter_bilinear = {
     .kernel = &pl_filter_function_triangle,
 };
 
@@ -646,10 +646,10 @@ const struct pl_named_filter_config pl_named_filters[] = {
     {"spline16",            &pl_filter_spline16},
     {"spline36",            &pl_filter_spline36},
     {"spline64",            &pl_filter_spline64},
-    {"box",                 &pl_filter_box},
-    {"nearest",             &pl_filter_box}, // alias
-    {"triangle",            &pl_filter_triangle},
-    {"bilinear",            &pl_filter_triangle}, // alias
+    {"nearest",             &pl_filter_nearest},
+    {"box",                 &pl_filter_nearest}, // alias
+    {"bilinear",            &pl_filter_bilinear},
+    {"triangle",            &pl_filter_bilinear}, // alias
     {"gaussian",            &pl_filter_gaussian},
     {"sinc",                &pl_filter_sinc},
     {"lanczos",             &pl_filter_lanczos},

src/include/libplacebo/filters.h

@@ -187,8 +187,8 @@ double pl_filter_sample(const struct pl_filter_config *c, double x);
 extern const struct pl_filter_config pl_filter_spline16;    // 2 taps
 extern const struct pl_filter_config pl_filter_spline36;    // 3 taps
 extern const struct pl_filter_config pl_filter_spline64;    // 4 taps
-extern const struct pl_filter_config pl_filter_box;         // AKA nearest
-extern const struct pl_filter_config pl_filter_triangle;    // AKA bilinear
+extern const struct pl_filter_config pl_filter_nearest;     // AKA box
+extern const struct pl_filter_config pl_filter_bilinear;    // AKA triangle
 extern const struct pl_filter_config pl_filter_gaussian;
 // Sinc family (all configured to 3 taps):
 extern const struct pl_filter_config pl_filter_sinc;        // unwindowed,
@@ -209,6 +209,10 @@ extern const struct pl_filter_config pl_filter_robidouxsharp;
 extern const struct pl_filter_config pl_filter_ewa_robidoux;
 extern const struct pl_filter_config pl_filter_ewa_robidouxsharp;
 
+// Backwards compatibility
+#define pl_filter_box       pl_filter_nearest
+#define pl_filter_triangle  pl_filter_bilinear
+
 struct pl_named_filter_config {
     const char *name;
     const struct pl_filter_config *filter;

src/include/libplacebo/renderer.h

@@ -76,7 +76,7 @@ struct pl_render_params {
     // since the built-in GPU sampling algorithms can't anti-alias.
     //
     // Note: If set to the same address as the built-in `pl_filter_bicubic`,
-    // `pl_filter_box` etc.; libplacebo will also use the more efficient
+    // `pl_filter_nearest` etc.; libplacebo will also use the more efficient
     // direct sampling algorithm where possible without quality loss.
     const struct pl_filter_config *upscaler;
     const struct pl_filter_config *downscaler;

src/renderer.c

@@ -480,9 +480,9 @@ static struct sampler_info sample_src_info(struct pl_renderer *rr,
         if (can_fast && !params->disable_builtin_scalers) {
             if (can_linear && info.config == &pl_filter_bicubic)
                 info.type = SAMPLER_BICUBIC;
-            if (can_linear && info.config == &pl_filter_triangle)
+            if (can_linear && info.config == &pl_filter_bilinear)
                 info.type = SAMPLER_DIRECT;
-            if (info.config == &pl_filter_box)
+            if (info.config == &pl_filter_nearest)
                 info.type = can_linear ? SAMPLER_NEAREST : SAMPLER_DIRECT;
         }
     }