Simulate and light the smoke on the GPU and make rain and snow of particles

shaders/particles_precipitation.frag

@@ -0,0 +1,46 @@
+// rain and snow of the gpu (opengl46_gpu_particles, particles_precipitation.vert): a streak rounded at its ends, fainter towards
+// its tail, in the colour the compute pass lit it with, faded in front of the scene, fogged
+
+in vec4 f_pos;
+in vec4 f_color;
+in vec4 f_streak;
+in float f_soft;
+
+in vec4 f_clip_pos;
+in vec4 f_clip_future_pos;
+
+#include <common>
+#include <apply_fog.glsl>
+#include <tonemapping.glsl>
+#include <particle_soft.glsl>
+
+layout(location = 0) out vec4 out_color;
+#if MOTIONBLUR_ENABLED
+layout(location = 1) out vec4 out_motion;
+#endif
+
+void main()
+{
+	// distance from the axis of the streak, in its radii
+	float along = clamp(f_streak.y, 0.0, f_streak.w);
+	float offaxis = length(vec2(f_streak.x, f_streak.y - along)) / max(f_streak.z, 1e-6);
+	float alpha = f_color.a * (1.0 - smoothstep(0.35, 1.0, offaxis));
+	alpha *= mix(1.0, 0.4, along / max(f_streak.w, 1e-6));
+	alpha *= particle_soft_fade(f_soft, -f_pos.z);
+	if (alpha <= 0.0)
+		discard;
+	vec4 color = vec4(apply_fog(f_color.rgb), alpha);
+#if POSTFX_ENABLED
+	out_color = color;
+#else
+	out_color = tonemap(color);
+#endif
+#if MOTIONBLUR_ENABLED
+	{
+		vec2 a = (f_clip_future_pos.xy / f_clip_future_pos.w) * 0.5 + 0.5;
+		vec2 b = (f_clip_pos.xy / f_clip_pos.w) * 0.5 + 0.5;
+
+		out_motion = vec4(a - b, 0.0f, alpha * alpha_mult);
+	}
+#endif
+}