render/vulkan: add Vulkan renderer

This new renderer is implemented with the existing wlr_renderer API
(which is known to be sub-optimal for some operations). It's not
used by default, but users can opt-in by setting WLR_RENDERER=vulkan.

The renderer depends on VK_EXT_image_drm_format_modifier and
VK_EXT_physical_device_drm.

Co-authored-by: Simon Ser <contact@emersion.fr>
Co-authored-by: Jan Beich <jbeich@FreeBSD.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/render/vulkan/shaders/texture.frag b/render/vulkan/shaders/texture.frag
new file mode 100644
index 00000000..7a7b8c57
--- /dev/null
+++ b/render/vulkan/shaders/texture.frag
@@ -0,0 +1,25 @@
+#version 450
+
+layout(set = 0, binding = 0) uniform sampler2D tex;
+
+layout(location = 0) in vec2 uv;
+layout(location = 0) out vec4 out_color;
+
+layout(push_constant) uniform UBO {
+	layout(offset = 80) float alpha;
+} data;
+
+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;
+	}
+}
+