Viewport: use depth shader to debug the depth

At the moment this already shows that the depth is the same after the solid plates and in the very end of drawing, while they should be different. Later on we can adapt this to show different buffers we want to debug.

I am using near=0.1, far=2.0 for my tests. I decided not to make a doversion for near/far because this is for debugging only

1 files changed, 75 insertions, 2 deletions

diff --git a/source/blender/editors/space_view3d/view3d_draw.c b/source/blender/editors/space_view3d/view3d_draw.c
index 4a2a04359f7..941315961b3 100644
--- a/source/blender/editors/space_view3d/view3d_draw.c
+++ b/source/blender/editors/space_view3d/view3d_draw.c
@@ -56,6 +56,8 @@
 #include "GPU_immediate.h"
 #include "GPU_viewport.h"
 
+#include "MEM_guardedalloc.h"
+
 #include "UI_interface.h"
 #include "UI_resources.h"
 
@@ -73,9 +75,10 @@ typedef struct DrawData {
 	bool render_border;
 	bool clip_border;
 	bool is_render;
+	GPUViewport *viewport;
 } DrawData;
 
-static void view3d_draw_data_init(const bContext *C, ARegion *ar, DrawData *draw_data)
+static void view3d_draw_data_init(const bContext *C, ARegion *ar, RegionView3D *rv3d, DrawData *draw_data)
 {
 	Scene *scene = CTX_data_scene(C);
 	View3D *v3d = CTX_wm_view3d(C);
@@ -84,6 +87,8 @@ static void view3d_draw_data_init(const bContext *C, ARegion *ar, DrawData *draw
 
 	draw_data->render_border = ED_view3d_calc_render_border(scene, v3d, ar, &draw_data->border_rect);
 	draw_data->clip_border = (draw_data->render_border && !BLI_rcti_compare(&ar->drawrct, &draw_data->border_rect));
+
+	draw_data->viewport = rv3d->viewport;
 }
 
 /* ******************** general functions ***************** */
@@ -266,6 +271,70 @@ static void view3d_stereo3d_setup(Scene *scene, View3D *v3d, ARegion *ar)
 	}
 }
 
+/* ******************** debug ***************** */
+
+static void view3d_draw_debug_store_depth(ARegion *ar, DrawData *draw_data)
+{
+	GPUViewport *viewport = draw_data->viewport;
+	GLint viewport_size[4];
+	glGetIntegerv(GL_VIEWPORT, viewport_size);
+
+	const int x = viewport_size[0];
+	const int y = viewport_size[1];
+	const int w = viewport_size[2];
+	const int h = viewport_size[3];
+
+	if (GPU_viewport_debug_depth_is_valid(viewport)) {
+		if ((GPU_viewport_debug_depth_width(viewport) != w) ||
+			(GPU_viewport_debug_depth_height(viewport) != h))
+		{
+			GPU_viewport_debug_depth_free(viewport);
+		}
+	}
+
+	if (!GPU_viewport_debug_depth_is_valid(viewport)) {
+		char error[256];
+		if (!GPU_viewport_debug_depth_create(viewport, w, h, 0, error)) {
+			fprintf(stderr, "Failed to create depth buffer for debug: %s\n", error);
+			return;
+		}
+	}
+
+	GPU_viewport_debug_depth_store(viewport, x, y);
+}
+
+static void view3d_draw_debug_post_solid(const bContext *C, ARegion *ar, DrawData *draw_data)
+{
+	View3D *v3d = CTX_wm_view3d(C);
+
+	if ((v3d->tmp_compat_flag & V3D_DEBUG_SHOW_SCENE_DEPTH) != 0) {
+		view3d_draw_debug_store_depth(ar, draw_data);
+	}
+}
+
+static void view3d_draw_debug(const bContext *C, ARegion *ar, DrawData *draw_data)
+{
+	View3D *v3d = CTX_wm_view3d(C);
+
+	if ((v3d->tmp_compat_flag & V3D_DEBUG_SHOW_COMBINED_DEPTH) != 0) {
+		/* store */
+		view3d_draw_debug_store_depth(ar, draw_data);
+	}
+
+	if (((v3d->tmp_compat_flag & V3D_DEBUG_SHOW_SCENE_DEPTH) != 0) ||
+		((v3d->tmp_compat_flag & V3D_DEBUG_SHOW_COMBINED_DEPTH) != 0))
+	{
+		/* draw */
+		if (GPU_viewport_debug_depth_is_valid(draw_data->viewport)) {
+			GPU_viewport_debug_depth_draw(draw_data->viewport, v3d->debug.znear, v3d->debug.zfar);
+		}
+	}
+	else {
+		/* cleanup */
+		GPU_viewport_debug_depth_free(draw_data->viewport);
+	}
+}
+
 /* ******************** view border ***************** */
 
 static void view3d_camera_border(
@@ -1481,6 +1550,9 @@ static void view3d_draw_solid_plates(const bContext *C, ARegion *ar, DrawData *d
 	if (draw_data->is_render) {
 		view3d_draw_render_draw(C, scene, ar, v3d, draw_data->clip_border, &draw_data->border_rect);
 	}
+
+	/* debug */
+	view3d_draw_debug_post_solid(C, ar, draw_data);
 }
 
 /**
@@ -1606,6 +1678,7 @@ static void view3d_draw_view(const bContext *C, ARegion *ar, DrawData *draw_data
 	view3d_draw_reference_images(C);
 	view3d_draw_manipulator(C);
 	view3d_draw_region_info(C, ar);
+	view3d_draw_debug(C, ar, draw_data);
 }
 
 void view3d_main_region_draw(const bContext *C, ARegion *ar)
@@ -1625,7 +1698,7 @@ void view3d_main_region_draw(const bContext *C, ARegion *ar)
 	 * before we even call the drawing routine, but let's move on for now (dfelinto)
 	 * but this is a provisory way to start seeing things in the viewport */
 	DrawData draw_data;
-	view3d_draw_data_init(C, ar, &draw_data);
+	view3d_draw_data_init(C, ar, rv3d, &draw_data);
 	view3d_draw_view(C, ar, &draw_data);
 
 	v3d->flag |= V3D_INVALID_BACKBUF;