Merge pull request scp-fs2open#6149 from Kestrellius/fix-headon-discr…

…epancies

Make headon transition behavior consistent between laser and glow bitmaps

code/weapon/weapons.cpp

@@ -8819,6 +8819,8 @@ void weapon_render(object* obj, model_draw_list *scene)
 				vm_vec_scale_add(&tailp, &obj->pos, &rotated_offset, laser_length);
 				vm_vec_scale_add(&headp, &tailp, &obj->orient.vec.fvec, laser_length);
 
+			float main_bitmap_alpha_mult = 1.0;
+
 			if (wip->laser_bitmap.first_frame >= 0) {					
 				gr_set_color_fast(&wip->laser_color_1);
 
@@ -8851,16 +8853,16 @@ void weapon_render(object* obj, model_draw_list *scene)
 				float scaled_head_radius = model_render_get_diameter_clamped_to_min_pixel_size(&headp, wip->laser_head_radius * radius_mult, wip->laser_min_pixel_size);
 				float scaled_tail_radius = model_render_get_diameter_clamped_to_min_pixel_size(&tailp, wip->laser_tail_radius * radius_mult, wip->laser_min_pixel_size);
 
-				int alpha = static_cast<int>(alphaf * 255.0f);
+				int alpha = fl2i(alphaf * 255.0f);
 
 				// render the head-on bitmap if appropriate and maybe adjust the main bitmap's alpha
 				if (wip->laser_headon_bitmap.first_frame >= 0) {
-					float main_bitmap_alpha_mult = weapon_render_headon_bitmap(obj, &headp, &tailp,
+					main_bitmap_alpha_mult = weapon_render_headon_bitmap(obj, &headp, &tailp,
 						wip->laser_headon_bitmap.first_frame + headon_framenum,
 						scaled_head_radius,
 						scaled_tail_radius,
 						alpha, alpha, alpha);
-					alpha = static_cast<int>(alphaf * main_bitmap_alpha_mult * 255.0);
+					alpha = fl2i(alphaf * main_bitmap_alpha_mult * 255.0);
 				}
 
 				batching_add_laser(
@@ -8944,20 +8946,26 @@ void weapon_render(object* obj, model_draw_list *scene)
 				float scaled_head_radius = model_render_get_diameter_clamped_to_min_pixel_size(&headp2, wip->laser_head_radius * radius_mult, wip->laser_min_pixel_size);
 				float scaled_tail_radius = model_render_get_diameter_clamped_to_min_pixel_size(&tailp2, wip->laser_tail_radius * radius_mult, wip->laser_min_pixel_size);
 
-				int r = static_cast<int>(static_cast<float>(c.red) * alphaf);
-				int g = static_cast<int>(static_cast<float>(c.green) * alphaf);
-				int b = static_cast<int>(static_cast<float>(c.blue) * alphaf);
+				int r = fl2i(i2fl(c.red) * alphaf);
+				int g = fl2i(i2fl(c.green) * alphaf);
+				int b = fl2i(i2fl(c.blue) * alphaf);
 
 				// render the head-on bitmap if appropriate and maybe adjust the main bitmap's alpha
 				if (wip->laser_glow_headon_bitmap.first_frame >= 0) {
-					float main_bitmap_alpha_mult = weapon_render_headon_bitmap(obj, &headp2, &tailp2,
+					float head_alpha = 1.0 - main_bitmap_alpha_mult;
+
+					r = (int)(r * head_alpha);   g = (int)(g * head_alpha);   b = (int)(b * head_alpha);
+
+					batching_add_laser(
 						wip->laser_glow_headon_bitmap.first_frame + headon_framenum,
+						&headp2,
 						scaled_head_radius * wip->laser_glow_head_scale,
+						&tailp2,
 						scaled_tail_radius * wip->laser_glow_tail_scale,
 						r, g, b);
-					r = static_cast<int>(static_cast<float>(c.red) * alphaf * main_bitmap_alpha_mult);
-					g = static_cast<int>(static_cast<float>(c.green) * alphaf * main_bitmap_alpha_mult);
-					b = static_cast<int>(static_cast<float>(c.blue) * alphaf * main_bitmap_alpha_mult);
+					r = fl2i(i2fl(c.red) * alphaf * main_bitmap_alpha_mult);
+					g = fl2i(i2fl(c.green) * alphaf * main_bitmap_alpha_mult);
+					b = fl2i(i2fl(c.blue) * alphaf * main_bitmap_alpha_mult);
 				}
 
 				batching_add_laser(