Re-Implement GPU particles on master.

-No new features yet
-Unlike godot 3.x, sorting happens using GPU

1 files changed, 82 insertions, 0 deletions

diff --git a/servers/rendering/rasterizer_rd/shaders/particles_copy.glsl b/servers/rendering/rasterizer_rd/shaders/particles_copy.glsl
new file mode 100644
index 0000000000..6c782b6045
--- /dev/null
+++ b/servers/rendering/rasterizer_rd/shaders/particles_copy.glsl
@@ -0,0 +1,82 @@
+#[compute]
+
+#version 450
+
+VERSION_DEFINES
+
+layout(local_size_x = 64, local_size_y = 1, local_size_z = 1) in;
+
+struct ParticleData {
+	mat4 xform;
+	vec3 velocity;
+	bool is_active;
+	vec4 color;
+	vec4 custom;
+};
+
+layout(set = 0, binding = 1, std430) restrict readonly buffer Particles {
+	ParticleData data[];
+}
+particles;
+
+layout(set = 0, binding = 2, std430) restrict writeonly buffer Transforms {
+	vec4 data[];
+}
+instances;
+
+#ifdef USE_SORT_BUFFER
+
+layout(set = 1, binding = 0, std430) restrict buffer SortBuffer {
+	vec2 data[];
+}
+sort_buffer;
+
+#endif // USE_SORT_BUFFER
+
+layout(push_constant, binding = 0, std430) uniform Params {
+	vec3 sort_direction;
+	uint total_particles;
+}
+params;
+
+void main() {
+#ifdef MODE_FILL_SORT_BUFFER
+
+	uint particle = gl_GlobalInvocationID.x;
+	if (particle >= params.total_particles) {
+		return; //discard
+	}
+
+	sort_buffer.data[particle].x = dot(params.sort_direction, particles.data[particle].xform[3].xyz);
+	sort_buffer.data[particle].y = float(particle);
+#endif
+
+#ifdef MODE_FILL_INSTANCES
+
+	uint particle = gl_GlobalInvocationID.x;
+	uint write_offset = gl_GlobalInvocationID.x * (3 + 1 + 1); //xform + color + custom
+
+	if (particle >= params.total_particles) {
+		return; //discard
+	}
+
+#ifdef USE_SORT_BUFFER
+	particle = uint(sort_buffer.data[particle].y); //use index from sort buffer
+#endif
+
+	mat4 txform;
+
+	if (particles.data[particle].is_active) {
+		txform = transpose(particles.data[particle].xform);
+	} else {
+		txform = mat4(vec4(0.0), vec4(0.0), vec4(0.0), vec4(0.0)); //zero scale, becomes invisible
+	}
+
+	instances.data[write_offset + 0] = txform[0];
+	instances.data[write_offset + 1] = txform[1];
+	instances.data[write_offset + 2] = txform[2];
+	instances.data[write_offset + 3] = particles.data[particle].color;
+	instances.data[write_offset + 4] = particles.data[particle].custom;
+
+#endif
+}