paint: fix mask apply

paint/shaders/mask_apply.kong

@@ -1,7 +1,7 @@
 
 #[set(everything)]
 const constants: {
-	empty: float4;
+	mask_opacity: float;
 };
 
 #[set(everything)]
@@ -33,6 +33,7 @@ fun mask_apply_vert(input: vert_in): vert_out {
 fun mask_apply_frag(input: vert_out): float4 {
 	var col0: float4 = sample_lod(tex0, sampler_linear, input.tex, 0.0);
 	var mask: float = sample_lod(texa, sampler_linear, input.tex, 0.0).r;
+	mask = lerp(1.0, mask, constants.mask_opacity);
 	return float4(col0.rgb, col0.a * mask);
 }
 

paint/sources/globals.h

@@ -60,6 +60,7 @@ i32              pipes_blending;
 i32              pipes_tex1w;
 i32              pipes_tex0_mask;
 i32              pipes_texa_mask;
+i32              pipes_opac_apply_mask;
 i32              pipes_tex0_merge_mask;
 i32              pipes_texa_merge_mask;
 i32              pipes_tex_colorid;

paint/sources/pipes.c

@@ -142,6 +142,8 @@ void pipes_init() {
 		gpu_pipeline_compile(pipes_apply_mask);
 		pipes_tex0_mask = 0;
 		pipes_texa_mask = 1;
+		pipes_offset           = 0;
+		pipes_opac_apply_mask  = pipes_get_constant_location("float");
 	}
 
 	{

paint/sources/slot_layer.c

@@ -273,6 +273,7 @@ void layers_apply_mask(slot_layer_t *l, slot_layer_t *m) {
 	gpu_set_pipeline(pipes_apply_mask);
 	gpu_set_texture(pipes_tex0_mask, layers_temp_image);
 	gpu_set_texture(pipes_texa_mask, m->texpaint);
+	gpu_set_float(pipes_opac_apply_mask, m->mask_opacity);
 	gpu_set_vertex_buffer(const_data_screen_aligned_vb);
 	gpu_set_index_buffer(const_data_screen_aligned_ib);
 	gpu_draw();