DRW: API for own versions of builtin GPU shaders

DRW_shader_get_builtin_shader can replace GPU_shader_get_builtin_shader
when we need to support clipping.

Use this for loose point & wire drawing in object mode,
clips edges in lattice edit mode.

8 files changed, 238 insertions, 17 deletions

diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index a305d18a592..c25d5564b21 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -55,6 +55,7 @@ set(INC_SYS
 set(SRC
 	intern/draw_anim_viz.c
 	intern/draw_armature.c
+	intern/draw_builtin_shader.c
 	intern/draw_cache.c
 	intern/draw_cache_impl_curve.c
 	intern/draw_cache_impl_displist.c
@@ -133,6 +134,7 @@ set(SRC
 
 	DRW_engine.h
 	intern/DRW_render.h
+	intern/draw_builtin_shader.h
 	intern/draw_cache.h
 	intern/draw_cache_impl.h
 	intern/draw_common.h
@@ -323,6 +325,8 @@ data_to_c_simple(modes/shaders/particle_strand_frag.glsl SRC)
 data_to_c_simple(modes/shaders/particle_strand_vert.glsl SRC)
 data_to_c_simple(modes/shaders/sculpt_mask_vert.glsl SRC)
 data_to_c_simple(modes/shaders/volume_velocity_vert.glsl SRC)
+data_to_c_simple(modes/shaders/drw_shader_3D_vert.glsl SRC)
+data_to_c_simple(modes/shaders/drw_shader_3D_smooth_color_vert.glsl SRC)
 
 data_to_c_simple(engines/gpencil/shaders/gpencil_fill_vert.glsl SRC)
 data_to_c_simple(engines/gpencil/shaders/gpencil_fill_frag.glsl SRC)
diff --git a/source/blender/draw/intern/draw_builtin_shader.c b/source/blender/draw/intern/draw_builtin_shader.c
new file mode 100644
index 00000000000..3f49f9d2731
--- /dev/null
+++ b/source/blender/draw/intern/draw_builtin_shader.c
@@ -0,0 +1,131 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ *
+ */
+
+/** \file draw_armature.c
+ *  \ingroup draw
+ * Draw manager versions of #eGPUBuiltinShader, see #GPU_shader_get_builtin_shader.
+ *
+ * Allows for modifications to shaders (currently only clipping support).
+ * Follow GPU_shader.h conventions to avoid annoyance.
+ */
+
+#include "BLI_utildefines.h"
+
+#include "GPU_shader.h"
+
+#include "DRW_render.h"
+
+#include "draw_builtin_shader.h"  /* own include */
+
+
+extern char datatoc_common_world_clip_lib_glsl[];
+
+extern char datatoc_drw_shader_3D_vert_glsl[];
+extern char datatoc_drw_shader_3D_smooth_color_vert_glsl[];
+
+extern char datatoc_gpu_shader_uniform_color_frag_glsl[];
+extern char datatoc_gpu_shader_3D_smooth_color_frag_glsl[];
+
+
+/* cache of built-in shaders (each is created on first use) */
+static struct {
+	GPUShader *builtin_shaders[GPU_NUM_BUILTIN_SHADERS];
+} g_sh_data[DRW_SHADER_SLOT_LEN - 1] = {{{NULL}}};
+
+static GPUShader *drw_shader_get_builtin_shader_clipped(eGPUBuiltinShader shader_id, bool *r_test_only)
+{
+	const char *world_clip_lib = datatoc_common_world_clip_lib_glsl;
+	const char *world_clip_def = "#define USE_WORLD_CLIP_PLANES\n";
+
+	if (r_test_only) {
+		*r_test_only = true;
+	}
+
+	GPUShader *shader = NULL;
+	switch (shader_id) {
+		case GPU_SHADER_3D_UNIFORM_COLOR:
+			if (r_test_only) {
+				break;
+			}
+			shader = DRW_shader_create_from_arrays({
+			        .vert = (const char *[]){world_clip_lib, datatoc_drw_shader_3D_vert_glsl, NULL},
+			        .frag = (const char *[]){datatoc_gpu_shader_uniform_color_frag_glsl, NULL},
+			        .defs = (const char *[]){world_clip_def, NULL}});
+			break;
+		case GPU_SHADER_3D_SMOOTH_COLOR:
+			if (r_test_only) {
+				break;
+			}
+			shader = DRW_shader_create_from_arrays({
+			        .vert = (const char *[]){world_clip_lib, datatoc_drw_shader_3D_smooth_color_vert_glsl, NULL},
+			        .frag = (const char *[]){datatoc_gpu_shader_3D_smooth_color_frag_glsl, NULL},
+			        .defs = (const char *[]){world_clip_def, NULL}});
+			break;
+		default:
+			/* Unsupported, caller asserts. */
+			if (r_test_only) {
+				*r_test_only = false;
+			}
+	}
+	return shader;
+}
+
+static bool drw_shader_get_builtin_shader_test_all(eGPUBuiltinShader shader_id)
+{
+	bool test = false;
+	drw_shader_get_builtin_shader_clipped(shader_id, &test);
+	return test;
+}
+
+GPUShader *DRW_shader_get_builtin_shader(eGPUBuiltinShader shader_id, eDRW_ShaderSlot slot)
+{
+	BLI_assert(drw_shader_get_builtin_shader_test_all(shader_id));
+	if (slot == DRW_SHADER_SLOT_DEFAULT) {
+		return GPU_shader_get_builtin_shader(shader_id);
+	}
+
+	GPUShader **builtin_shaders = g_sh_data[slot - 1].builtin_shaders;
+
+	if (builtin_shaders[shader_id] != NULL) {
+		return builtin_shaders[shader_id];
+	}
+
+	if (slot == DRW_SHADER_SLOT_CLIPPED) {
+		builtin_shaders[shader_id] = drw_shader_get_builtin_shader_clipped(shader_id, NULL);
+		return builtin_shaders[shader_id];
+	}
+	else {
+		BLI_assert(0);
+	}
+}
+
+void DRW_shader_free_builtin_shaders(void)
+{
+	for (int j = 0; j < (DRW_SHADER_SLOT_LEN - 1); j++) {
+		GPUShader **builtin_shaders = g_sh_data[j].builtin_shaders;
+		for (int i = 0; i < GPU_NUM_BUILTIN_SHADERS; i++) {
+			if (builtin_shaders[i]) {
+				GPU_shader_free(builtin_shaders[i]);
+				builtin_shaders[i] = NULL;
+			}
+		}
+	}
+}
diff --git a/source/blender/draw/intern/draw_builtin_shader.h b/source/blender/draw/intern/draw_builtin_shader.h
new file mode 100644
index 00000000000..f9eb42a7026
--- /dev/null
+++ b/source/blender/draw/intern/draw_builtin_shader.h
@@ -0,0 +1,34 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ *
+ */
+
+/** \file draw_builtin_shader.h
+ *  \ingroup draw
+ */
+
+#ifndef __DRAW_BUILTIN_SHADER_H__
+#define __DRAW_BUILTIN_SHADER_H__
+
+struct GPUShader;
+
+struct GPUShader *DRW_shader_get_builtin_shader(eGPUBuiltinShader shader_id, eDRW_ShaderSlot slot);
+void DRW_shader_free_builtin_shaders(void);
+
+#endif  /* __DRAW_BUILTIN_SHADER_H__ */
diff --git a/source/blender/draw/intern/draw_manager.c b/source/blender/draw/intern/draw_manager.c
index c47ab00c841..d311b3e8156 100644
--- a/source/blender/draw/intern/draw_manager.c
+++ b/source/blender/draw/intern/draw_manager.c
@@ -82,6 +82,7 @@
 #include "draw_cache_impl.h"
 
 #include "draw_mode_engines.h"
+#include "draw_builtin_shader.h"
 #include "engines/eevee/eevee_engine.h"
 #include "engines/basic/basic_engine.h"
 #include "engines/workbench/workbench_engine.h"
@@ -2610,6 +2611,7 @@ void DRW_engines_free(void)
 	DRW_shape_cache_free();
 	DRW_stats_free();
 	DRW_globals_free();
+	DRW_shader_free_builtin_shaders();
 
 	DrawEngineType *next;
 	for (DrawEngineType *type = DRW_engines.first; type; type = next) {
diff --git a/source/blender/draw/modes/edit_lattice_mode.c b/source/blender/draw/modes/edit_lattice_mode.c
index c98a68f13b2..e484b359b9e 100644
--- a/source/blender/draw/modes/edit_lattice_mode.c
+++ b/source/blender/draw/modes/edit_lattice_mode.c
@@ -37,6 +37,7 @@
 #include "draw_common.h"
 
 #include "draw_mode_engines.h"
+#include "draw_builtin_shader.h"
 
 extern char datatoc_common_world_clip_lib_glsl[];
 extern char datatoc_common_globals_lib_glsl[];
@@ -154,7 +155,7 @@ static void EDIT_LATTICE_engine_init(void *vedata)
 	const char *world_clip_def_or_empty = is_clip ? "#define USE_WORLD_CLIP_PLANES\n" : "";
 
 	if (!sh_data->wire) {
-		sh_data->wire = GPU_shader_get_builtin_shader(GPU_SHADER_3D_SMOOTH_COLOR);
+		sh_data->wire = DRW_shader_get_builtin_shader(GPU_SHADER_3D_SMOOTH_COLOR, draw_ctx->shader_slot);
 	}
 
 	if (!sh_data->overlay_vert) {
@@ -194,6 +195,9 @@ static void EDIT_LATTICE_cache_init(void *vedata)
 		        "Lattice Wire",
 		        DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS_EQUAL | DRW_STATE_WIRE);
 		stl->g_data->wire_shgrp = DRW_shgroup_create(sh_data->wire, psl->wire_pass);
+		if (rv3d->rflag & RV3D_CLIPPING) {
+			DRW_shgroup_world_clip_planes_from_rv3d(stl->g_data->wire_shgrp, rv3d);
+		}
 
 		psl->vert_pass = DRW_pass_create(
 		        "Lattice Verts",
diff --git a/source/blender/draw/modes/object_mode.c b/source/blender/draw/modes/object_mode.c
index 7a10763c1b7..1f0bb4738db 100644
--- a/source/blender/draw/modes/object_mode.c
+++ b/source/blender/draw/modes/object_mode.c
@@ -79,9 +79,11 @@
 #include "draw_mode_engines.h"
 #include "draw_manager_text.h"
 #include "draw_common.h"
+#include "draw_builtin_shader.h"
 
 #include "DEG_depsgraph_query.h"
 
+extern char datatoc_common_world_clip_lib_glsl[];
 extern char datatoc_object_outline_prepass_vert_glsl[];
 extern char datatoc_object_outline_prepass_geom_glsl[];
 extern char datatoc_object_outline_prepass_frag_glsl[];
@@ -103,6 +105,7 @@ extern char datatoc_gpu_shader_flat_color_frag_glsl[];
 extern char datatoc_gpu_shader_flat_id_frag_glsl[];
 extern char datatoc_common_fullscreen_vert_glsl[];
 extern char datatoc_gpu_shader_uniform_color_frag_glsl[];
+extern char datatoc_drw_shader_3D_vert_glsl[];
 
 /* *********** LISTS *********** */
 typedef struct OBJECT_PassList {
@@ -409,6 +412,10 @@ static void OBJECT_engine_init(void *vedata)
 	const DRWContextState *draw_ctx = DRW_context_state_get();
 	OBJECT_Shaders *sh_data = &e_data.sh_data[draw_ctx->shader_slot];
 
+	const bool is_clip = (draw_ctx->rv3d->rflag & RV3D_CLIPPING) != 0;
+	const char *world_clip_lib_or_empty = is_clip ? datatoc_common_world_clip_lib_glsl : "";
+	const char *world_clip_def_or_empty = is_clip ? "#define USE_WORLD_CLIP_PLANES\n" : "";
+
 	if (!sh_data->outline_resolve) {
 		/* Outline */
 		sh_data->outline_prepass = DRW_shader_create_3D(datatoc_object_outline_prepass_frag_glsl, NULL);
@@ -484,7 +491,10 @@ static void OBJECT_engine_init(void *vedata)
 		        datatoc_object_lightprobe_grid_vert_glsl, NULL, datatoc_gpu_shader_flat_id_frag_glsl, NULL);
 
 		/* Loose Points */
-		sh_data->loose_points = DRW_shader_create_3D(datatoc_object_loose_points_frag_glsl, NULL);
+		sh_data->loose_points = DRW_shader_create_from_arrays({
+		        .vert = (const char *[]){world_clip_lib_or_empty, datatoc_drw_shader_3D_vert_glsl, NULL},
+		        .frag = (const char *[]){datatoc_object_loose_points_frag_glsl, NULL},
+		        .defs = (const char *[]){world_clip_def_or_empty, NULL}});
 	}
 
 	{
@@ -664,21 +674,27 @@ static DRWShadingGroup *shgroup_outline(DRWPass *pass, const int *ofs, GPUShader
 }
 
 /* currently same as 'shgroup_outline', new function to avoid confustion */
-static DRWShadingGroup *shgroup_wire(DRWPass *pass, const float col[4], GPUShader *sh)
+static DRWShadingGroup *shgroup_wire(DRWPass *pass, const float col[4], GPUShader *sh, eDRW_ShaderSlot shader_slot)
 {
 	DRWShadingGroup *grp = DRW_shgroup_create(sh, pass);
 	DRW_shgroup_uniform_vec4(grp, "color", col, 1);
 
+	if (shader_slot == DRW_SHADER_SLOT_CLIPPED) {
+		DRW_shgroup_world_clip_planes_from_rv3d(grp, DRW_context_state_get()->rv3d);
+	}
 	return grp;
 }
 
 /* currently same as 'shgroup_outline', new function to avoid confustion */
-static DRWShadingGroup *shgroup_points(DRWPass *pass, const float col[4], GPUShader *sh)
+static DRWShadingGroup *shgroup_points(DRWPass *pass, const float col[4], GPUShader *sh, eDRW_ShaderSlot shader_slot)
 {
 	DRWShadingGroup *grp = DRW_shgroup_create(sh, pass);
 	DRW_shgroup_uniform_vec4(grp, "color", col, 1);
 	DRW_shgroup_uniform_vec4(grp, "innerColor", G_draw.block.colorEditMeshMiddle, 1);
 
+	if (shader_slot == DRW_SHADER_SLOT_CLIPPED) {
+		DRW_shgroup_world_clip_planes_from_rv3d(grp, DRW_context_state_get()->rv3d);
+	}
 	return grp;
 }
 
@@ -1252,24 +1268,24 @@ static void OBJECT_cache_init(void *vedata)
 		sgl->texspace = shgroup_instance(sgl->non_meshes, geom);
 
 		/* Wires (for loose edges) */
-		sh = GPU_shader_get_builtin_shader(GPU_SHADER_3D_UNIFORM_COLOR);
-		sgl->wire = shgroup_wire(sgl->non_meshes, gb->colorWire, sh);
-		sgl->wire_select = shgroup_wire(sgl->non_meshes, gb->colorSelect, sh);
-		sgl->wire_transform = shgroup_wire(sgl->non_meshes, gb->colorTransform, sh);
-		sgl->wire_active = shgroup_wire(sgl->non_meshes, gb->colorActive, sh);
+		sh = DRW_shader_get_builtin_shader(GPU_SHADER_3D_UNIFORM_COLOR, draw_ctx->shader_slot);
+		sgl->wire = shgroup_wire(sgl->non_meshes, gb->colorWire, sh, draw_ctx->shader_slot);
+		sgl->wire_select = shgroup_wire(sgl->non_meshes, gb->colorSelect, sh, draw_ctx->shader_slot);
+		sgl->wire_transform = shgroup_wire(sgl->non_meshes, gb->colorTransform, sh, draw_ctx->shader_slot);
+		sgl->wire_active = shgroup_wire(sgl->non_meshes, gb->colorActive, sh, draw_ctx->shader_slot);
 		/* Wire (duplicator) */
-		sgl->wire_dupli = shgroup_wire(sgl->non_meshes, gb->colorDupli, sh);
-		sgl->wire_dupli_select = shgroup_wire(sgl->non_meshes, gb->colorDupliSelect, sh);
+		sgl->wire_dupli = shgroup_wire(sgl->non_meshes, gb->colorDupli, sh, draw_ctx->shader_slot);
+		sgl->wire_dupli_select = shgroup_wire(sgl->non_meshes, gb->colorDupliSelect, sh, draw_ctx->shader_slot);
 
 		/* Points (loose points) */
 		sh = sh_data->loose_points;
-		sgl->points = shgroup_points(sgl->non_meshes, gb->colorWire, sh);
-		sgl->points_select = shgroup_points(sgl->non_meshes, gb->colorSelect, sh);
-		sgl->points_transform = shgroup_points(sgl->non_meshes, gb->colorTransform, sh);
-		sgl->points_active = shgroup_points(sgl->non_meshes, gb->colorActive, sh);
+		sgl->points = shgroup_points(sgl->non_meshes, gb->colorWire, sh, draw_ctx->shader_slot);
+		sgl->points_select = shgroup_points(sgl->non_meshes, gb->colorSelect, sh, draw_ctx->shader_slot);
+		sgl->points_transform = shgroup_points(sgl->non_meshes, gb->colorTransform, sh, draw_ctx->shader_slot);
+		sgl->points_active = shgroup_points(sgl->non_meshes, gb->colorActive, sh, draw_ctx->shader_slot);
 		/* Points (duplicator) */
-		sgl->points_dupli = shgroup_points(sgl->non_meshes, gb->colorDupli, sh);
-		sgl->points_dupli_select = shgroup_points(sgl->non_meshes, gb->colorDupliSelect, sh);
+		sgl->points_dupli = shgroup_points(sgl->non_meshes, gb->colorDupli, sh, draw_ctx->shader_slot);
+		sgl->points_dupli_select = shgroup_points(sgl->non_meshes, gb->colorDupliSelect, sh, draw_ctx->shader_slot);
 		DRW_shgroup_state_disable(sgl->points, DRW_STATE_BLEND);
 		DRW_shgroup_state_disable(sgl->points_select, DRW_STATE_BLEND);
 		DRW_shgroup_state_disable(sgl->points_transform, DRW_STATE_BLEND);
diff --git a/source/blender/draw/modes/shaders/drw_shader_3D_smooth_color_vert.glsl b/source/blender/draw/modes/shaders/drw_shader_3D_smooth_color_vert.glsl
new file mode 100644
index 00000000000..05f9618a7f7
--- /dev/null
+++ b/source/blender/draw/modes/shaders/drw_shader_3D_smooth_color_vert.glsl
@@ -0,0 +1,17 @@
+/* Keep 'gpu_shader_3D_smooth_color_vert.glsl' compatible. */
+uniform mat4 ModelViewProjectionMatrix;
+uniform mat4 ModelMatrix;
+
+in vec3 pos;
+in vec4 color;
+
+out vec4 finalColor;
+
+void main()
+{
+	gl_Position = ModelViewProjectionMatrix * vec4(pos, 1.0);
+	finalColor = color;
+#ifdef USE_WORLD_CLIP_PLANES
+       world_clip_planes_calc_clip_distance((ModelMatrix * vec4(pos, 1.0)).xyz);
+#endif
+}
diff --git a/source/blender/draw/modes/shaders/drw_shader_3D_vert.glsl b/source/blender/draw/modes/shaders/drw_shader_3D_vert.glsl
new file mode 100644
index 00000000000..f0d477527ce
--- /dev/null
+++ b/source/blender/draw/modes/shaders/drw_shader_3D_vert.glsl
@@ -0,0 +1,13 @@
+/* Keep 'gpu_shader_3D_vert.glsl' compatible. */
+uniform mat4 ModelViewProjectionMatrix;
+uniform mat4 ModelMatrix;
+
+in vec3 pos;
+
+void main()
+{
+	gl_Position = ModelViewProjectionMatrix * vec4(pos, 1.0);
+#ifdef USE_WORLD_CLIP_PLANES
+       world_clip_planes_calc_clip_distance((ModelMatrix * vec4(pos, 1.0)).xyz);
+#endif
+}