From 340e4394d43e8c3eed6ef84dafb4093299f22a29 Mon Sep 17 00:00:00 2001
From: Luca Rood <dev@lucarood.com>
Date: Tue, 23 May 2017 14:25:12 +0200
Subject: [PATCH] Use custom shader for dot particles

---
 source/blender/draw/CMakeLists.txt            |  2 ++
 source/blender/draw/modes/object_mode.c       |  5 ++-
 .../shaders/object_particle_dot_frag.glsl     | 36 +++++++++++++++++++
 .../shaders/object_particle_dot_vert.glsl     | 23 ++++++++++++
 4 files changed, 65 insertions(+), 1 deletion(-)
 create mode 100644 source/blender/draw/modes/shaders/object_particle_dot_frag.glsl
 create mode 100644 source/blender/draw/modes/shaders/object_particle_dot_vert.glsl

diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index 4b4307f2bd5..a8a6d3144ca 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -164,6 +164,8 @@ data_to_c_simple(modes/shaders/object_grid_frag.glsl SRC)
 data_to_c_simple(modes/shaders/object_grid_vert.glsl SRC)
 data_to_c_simple(modes/shaders/object_particle_prim_vert.glsl SRC)
 data_to_c_simple(modes/shaders/object_particle_prim_frag.glsl SRC)
+data_to_c_simple(modes/shaders/object_particle_dot_vert.glsl SRC)
+data_to_c_simple(modes/shaders/object_particle_dot_frag.glsl SRC)
 data_to_c_simple(modes/shaders/paint_texture_frag.glsl SRC)
 data_to_c_simple(modes/shaders/paint_texture_vert.glsl SRC)
 data_to_c_simple(modes/shaders/paint_wire_frag.glsl SRC)
diff --git a/source/blender/draw/modes/object_mode.c b/source/blender/draw/modes/object_mode.c
index dbc18e19b41..ee95d4a0598 100644
--- a/source/blender/draw/modes/object_mode.c
+++ b/source/blender/draw/modes/object_mode.c
@@ -68,6 +68,8 @@ extern char datatoc_object_empty_image_frag_glsl[];
 extern char datatoc_object_empty_image_vert_glsl[];
 extern char datatoc_object_particle_prim_vert_glsl[];
 extern char datatoc_object_particle_prim_frag_glsl[];
+extern char datatoc_object_particle_dot_vert_glsl[];
+extern char datatoc_object_particle_dot_frag_glsl[];
 extern char datatoc_common_globals_lib_glsl[];
 
 /* *********** LISTS *********** */
@@ -290,7 +292,7 @@ static void OBJECT_engine_init(void *vedata)
 	}
 
 	if (!e_data.part_dot_sh) {
-		e_data.part_dot_sh = GPU_shader_get_builtin_shader(GPU_SHADER_3D_POINT_UNIFORM_SIZE_UNIFORM_COLOR_OUTLINE_AA);
+		e_data.part_dot_sh = DRW_shader_create(datatoc_object_particle_dot_vert_glsl, NULL, datatoc_object_particle_dot_frag_glsl, NULL);
 	}
 
 	{
@@ -438,6 +440,7 @@ static void OBJECT_engine_free(void)
 	DRW_SHADER_FREE_SAFE(e_data.object_empty_image_wire_sh);
 	DRW_SHADER_FREE_SAFE(e_data.grid_sh);
 	DRW_SHADER_FREE_SAFE(e_data.part_prim_sh);
+	DRW_SHADER_FREE_SAFE(e_data.part_dot_sh);
 }
 
 static DRWShadingGroup *shgroup_outline(DRWPass *pass, const float col[4], GPUShader *sh)
diff --git a/source/blender/draw/modes/shaders/object_particle_dot_frag.glsl b/source/blender/draw/modes/shaders/object_particle_dot_frag.glsl
new file mode 100644
index 00000000000..eae5ee633ae
--- /dev/null
+++ b/source/blender/draw/modes/shaders/object_particle_dot_frag.glsl
@@ -0,0 +1,36 @@
+
+uniform vec4 color;
+uniform vec4 outlineColor;
+
+in vec4 radii;
+out vec4 fragColor;
+
+void main() {
+	float dist = length(gl_PointCoord - vec2(0.5));
+
+// transparent outside of point
+// --- 0 ---
+// smooth transition
+// --- 1 ---
+// pure outline color
+// --- 2 ---
+// smooth transition
+// --- 3 ---
+// pure point color
+// ...
+// dist = 0 at center of point
+
+	float midStroke = 0.5 * (radii[1] + radii[2]);
+
+	if (dist > midStroke) {
+		fragColor.rgb = outlineColor.rgb;
+		fragColor.a = mix(outlineColor.a, 0.0, smoothstep(radii[1], radii[0], dist));
+	}
+	else {
+		fragColor = mix(color, outlineColor, smoothstep(radii[3], radii[2], dist));
+	}
+
+	if (fragColor.a == 0.0) {
+		discard;
+	}
+}
diff --git a/source/blender/draw/modes/shaders/object_particle_dot_vert.glsl b/source/blender/draw/modes/shaders/object_particle_dot_vert.glsl
new file mode 100644
index 00000000000..d9d30c8e677
--- /dev/null
+++ b/source/blender/draw/modes/shaders/object_particle_dot_vert.glsl
@@ -0,0 +1,23 @@
+
+uniform mat4 ModelViewProjectionMatrix;
+uniform float size;
+
+in vec3 pos;
+out vec4 radii;
+
+void main() {
+	gl_Position = ModelViewProjectionMatrix * vec4(pos, 1.0);
+	gl_PointSize = size;
+
+	// calculate concentric radii in pixels
+	float radius = 0.5 * size;
+
+	// start at the outside and progress toward the center
+	radii[0] = radius;
+	radii[1] = radius - 1.0;
+	radii[2] = radius - 1.0;
+	radii[3] = radius - 2.0;
+
+	// convert to PointCoord units
+	radii /= size;
+}