soft particles

src/mirrage/renderer/shader/particle.vert

@@ -19,6 +19,7 @@ layout(location = 0) out vec3 out_view_pos;
 layout(location = 1) out vec3 out_normal;
 layout(location = 2) out vec2 out_tex_coords;
 layout(location = 3) out vec4 out_particle_color;
+layout(location = 4) out vec4 out_screen_pos;
 
 layout(std140, set=2, binding = 0) readonly buffer Particle_type_config {
 	PARTICLE_TYPE_CONFIG
@@ -163,5 +164,7 @@ void main() {
 	vec4 color = calc_color(keyframe_a, keyframe_b, keyframe_t, rand_color);;
 	out_particle_color = vec4(hsv2rgb(color.xyz), color.a);
 
-	gl_Position = global_uniforms.proj_mat * view_pos;
+	vec4 screen_pos = global_uniforms.proj_mat * view_pos;
+	out_screen_pos = screen_pos;
+	gl_Position = screen_pos;
 }

src/mirrage/renderer/shader/particle_transparent_lit.frag

@@ -12,6 +12,7 @@ layout(location = 0) in vec3 view_pos;
 layout(location = 1) in vec3 normal;
 layout(location = 2) in vec2 tex_coords;
 layout(location = 3) in vec4 out_particle_color;
+layout(location = 4) in vec4 out_screen_pos;
 
 layout(location = 0) out vec4 accum_out;
 layout(location = 1) out vec4 revealage_out;
@@ -25,10 +26,13 @@ layout(std140, set=2, binding = 0) readonly buffer Particle_type_config {
 	PARTICLE_TYPE_CONFIG
 } particle_config;
 
+layout(set=3, binding = 0) uniform sampler2D depth_sampler;
+
 layout(push_constant) uniform Per_model_uniforms {
 	mat4 model;
 	vec4 light_color;
 	vec4 options;
+	vec4 light_data2; // R=shadowmapID
 } model_uniforms;
 
 const float PI = 3.14159265359;
@@ -38,9 +42,15 @@ vec3 decode_tangent_normal(vec2 tn);
 vec3 tangent_space_to_world(vec3 N);
 
 void main() {
+	int mip = int(model_uniforms.light_data2.w);
+
 	vec4 albedo = texture(albedo_sampler, tex_coords);
 	albedo *= out_particle_color;
 
+	vec2 screen_uv = out_screen_pos.xy/out_screen_pos.w*0.5+0.5;
+	float background_depth = textureLod(depth_sampler, screen_uv, mip).r * -global_uniforms.proj_planes.y;
+	albedo.a *= smoothstep(0, 0.5, abs(background_depth-view_pos.z));
+
 	if(albedo.a<0.001) {
 		discard;
 	}