render/vulkan: Use image view swizzles instead of shader hack

Signed-off-by: Joshua Ashton <joshua@froggi.es>

render/vulkan/renderer.c

@@ -794,17 +794,6 @@ static bool vulkan_render_subtexture_with_matrix(struct wlr_renderer *wlr_render
 		vert_pcr_data.uv_size[1] = -vert_pcr_data.uv_size[1];
 	}
 
-	// When the texture itself does not have alpha information we want
-	// to ignore the sampled value and just use the alpha passed here,
-	// we pass a negative value to communicate that.
-	// See the texture.frag shader for more details.
-	const struct wlr_pixel_format_info *format_info = drm_get_pixel_format_info(
-			texture->format->drm_format);
-	assert(format_info);
-	if (!format_info->has_alpha) {
-		alpha *= -1;
-	}
-
 	vkCmdPushConstants(cb, renderer->pipe_layout,
 		VK_SHADER_STAGE_VERTEX_BIT, 0, sizeof(vert_pcr_data), &vert_pcr_data);
 	vkCmdPushConstants(cb, renderer->pipe_layout,

render/vulkan/shaders/texture.frag

@@ -11,15 +11,6 @@ layout(push_constant) uniform UBO {
 
 void main() {
 	out_color = textureLod(tex, uv, 0);
-
-	// We expect this shader to output pre-alpha-multiplied color values.
-	// alpha < 0.0 means that this shader should ignore the texture's alpha
-	// value.
-	if (data.alpha < 0.0) {
-		out_color.a = -data.alpha;
-		out_color.rgb *= -data.alpha;
-	} else {
 	out_color *= data.alpha;
 }
-}
 

render/vulkan/texture.c

@@ -288,6 +288,9 @@ static struct wlr_texture *vulkan_texture_from_pixels(struct wlr_renderer *wlr_r
 		goto error;
 	}
 
+	const struct wlr_pixel_format_info *format_info = drm_get_pixel_format_info(drm_fmt);
+	assert(format_info);
+
 	// view
 	VkImageViewCreateInfo view_info = {0};
 	view_info.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
@@ -296,7 +299,9 @@ static struct wlr_texture *vulkan_texture_from_pixels(struct wlr_renderer *wlr_r
 	view_info.components.r = VK_COMPONENT_SWIZZLE_IDENTITY;
 	view_info.components.g = VK_COMPONENT_SWIZZLE_IDENTITY;
 	view_info.components.b = VK_COMPONENT_SWIZZLE_IDENTITY;
-	view_info.components.a = VK_COMPONENT_SWIZZLE_IDENTITY;
+	view_info.components.a = format_info->has_alpha
+		? VK_COMPONENT_SWIZZLE_IDENTITY
+		: VK_COMPONENT_SWIZZLE_ONE;
 
 	view_info.subresourceRange = (VkImageSubresourceRange) {
 		VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1
@@ -613,6 +618,9 @@ static struct wlr_texture *vulkan_texture_from_dmabuf(struct wlr_renderer *wlr_r
 		// return VK_NULL_HANDLE;
 	}
 
+	const struct wlr_pixel_format_info *format_info = drm_get_pixel_format_info(attribs->format);
+	assert(format_info);
+
 	// view
 	VkImageViewCreateInfo view_info = {0};
 	view_info.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
@@ -621,7 +629,9 @@ static struct wlr_texture *vulkan_texture_from_dmabuf(struct wlr_renderer *wlr_r
 	view_info.components.r = VK_COMPONENT_SWIZZLE_IDENTITY;
 	view_info.components.g = VK_COMPONENT_SWIZZLE_IDENTITY;
 	view_info.components.b = VK_COMPONENT_SWIZZLE_IDENTITY;
-	view_info.components.a = VK_COMPONENT_SWIZZLE_IDENTITY;
+	view_info.components.a = format_info->has_alpha
+		? VK_COMPONENT_SWIZZLE_IDENTITY
+		: VK_COMPONENT_SWIZZLE_ONE;
 
 	view_info.subresourceRange = (VkImageSubresourceRange) {
 		VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1