vrend: fix shadow_samp_*_locs index incrementing

Commit 603699f1 ("vrend: Cleanup and fix bug in next_sampler_id
tracking") fixed a rendering issue in Factorio but inadvertently changed
the indexing behavior for shadow samplers in some related code cleaning.

shadow_samp_*_locs arrays are currently indexed according to the bit
position of a sampler in samplers_used_mask and shadow_samp_mask, so
sampler_index must be incremented for each sampler, not just for each
shadow sampler.

Fixes: 603699f1 ("vrend: Cleanup and fix bug in next_sampler_id tracking")

Signed-off-by: Ryan Neph <ryanneph@google.com>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>

src/vrend_renderer.c

@@ -4292,7 +4292,7 @@ static int vrend_draw_bind_samplers_shader(struct vrend_sub_context *sub_ctx,
                                            int shader_type,
                                            int next_sampler_id)
 {
-   int index = 0;
+   int sampler_index = 0;
    int n_samplers = 0;
    uint32_t dirty = sub_ctx->sampler_views_dirty[shader_type];
    uint32_t mask = sub_ctx->prog->samplers_used_mask[shader_type];
@@ -4304,17 +4304,16 @@ static int vrend_draw_bind_samplers_shader(struct vrend_sub_context *sub_ctx,
       struct vrend_sampler_view *tview = sviews->views[i];
       if ((dirty & (1 << i)) && tview) {
          if (sub_ctx->prog->shadow_samp_mask[shader_type] & (1 << i)) {
-            glUniform4f(sub_ctx->prog->shadow_samp_mask_locs[shader_type][index],
+            glUniform4f(sub_ctx->prog->shadow_samp_mask_locs[shader_type][sampler_index],
                         (tview->gl_swizzle[0] == GL_ZERO || tview->gl_swizzle[0] == GL_ONE) ? 0.0 : 1.0,
                         (tview->gl_swizzle[1] == GL_ZERO || tview->gl_swizzle[1] == GL_ONE) ? 0.0 : 1.0,
                         (tview->gl_swizzle[2] == GL_ZERO || tview->gl_swizzle[2] == GL_ONE) ? 0.0 : 1.0,
                         (tview->gl_swizzle[3] == GL_ZERO || tview->gl_swizzle[3] == GL_ONE) ? 0.0 : 1.0);
-            glUniform4f(sub_ctx->prog->shadow_samp_add_locs[shader_type][index],
+            glUniform4f(sub_ctx->prog->shadow_samp_add_locs[shader_type][sampler_index],
                         tview->gl_swizzle[0] == GL_ONE ? 1.0 : 0.0,
                         tview->gl_swizzle[1] == GL_ONE ? 1.0 : 0.0,
                         tview->gl_swizzle[2] == GL_ONE ? 1.0 : 0.0,
                         tview->gl_swizzle[3] == GL_ONE ? 1.0 : 0.0);
-            index++;
          }
 
          if (tview->texture) {
@@ -4346,6 +4345,7 @@ static int vrend_draw_bind_samplers_shader(struct vrend_sub_context *sub_ctx,
             dirty &= ~(1 << i);
          }
       }
+      sampler_index++;
       next_sampler_id++;
    }