gallium: remove always-false parameter

We always pass false to util_map_texcoords2d_onto_cubemap function, which
allows us to avoid the dodgy case of using a close-to-one scaling factor
in an attempt to avoid sampling on the edges.

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27759>

src/gallium/auxiliary/util/u_blitter.c

@@ -1831,8 +1831,7 @@ blitter_draw_tex(struct blitter_context_priv *ctx,
       util_map_texcoords2d_onto_cubemap((unsigned)layer % 6,
                                         /* pointer, stride in floats */
                                         &face_coord[0][0], 2,
-                                        &ctx->vertices[0][1][0], 8,
-                                        false);
+                                        &ctx->vertices[0][1][0], 8);
       for (unsigned i = 0; i < 4; i++)
          ctx->vertices[i][1][3] = coord.texcoord.w;
 

src/gallium/auxiliary/util/u_texture.c

@@ -42,27 +42,15 @@
 
 void util_map_texcoords2d_onto_cubemap(unsigned face,
                                        const float *in_st, unsigned in_stride,
-                                       float *out_str, unsigned out_stride,
-                                       bool allow_scale)
+                                       float *out_str, unsigned out_stride)
 {
    int i;
    float rx, ry, rz;
 
    /* loop over quad verts */
    for (i = 0; i < 4; i++) {
-      /* Compute sc = +/-scale and tc = +/-scale.
-       * Not +/-1 to avoid cube face selection ambiguity near the edges,
-       * though that can still sometimes happen with this scale factor...
-       *
-       * XXX: Yep, there is no safe scale factor that will prevent sampling
-       * the neighbouring face when stretching out.  A more reliable solution
-       * would be to clamp (sc, tc) against +/- 1.0-1.0/mipsize, in the shader.
-       *
-       * Also, this is not necessary when minifying, or 1:1 blits.
-       */
-      const float scale = allow_scale ? 0.9999f : 1.0f;
-      const float sc = (2 * in_st[0] - 1) * scale;
-      const float tc = (2 * in_st[1] - 1) * scale;
+      const float sc = 2 * in_st[0] - 1;
+      const float tc = 2 * in_st[1] - 1;
 
       switch (face) {
          case PIPE_TEX_FACE_POS_X:

src/gallium/auxiliary/util/u_texture.h

@@ -46,8 +46,7 @@ extern "C" {
  */
 void util_map_texcoords2d_onto_cubemap(unsigned face,
                                        const float *in_st, unsigned in_stride,
-                                       float *out_str, unsigned out_stride,
-                                       bool allow_scale);
+                                       float *out_str, unsigned out_stride);
 
 
 #ifdef __cplusplus