OpenGL: shaders for smooth round points

Solid color with an optional outline.

size (diameter) and outlineWidth are in pixels.

source/blender/gpu/shaders/gpu_shader_2D_point_uniform_size_uniform_color_outline_smooth_vert.glsl

@@ -0,0 +1,28 @@
+
+uniform float size;
+uniform float outlineWidth;
+
+#if __VERSION__ == 120
+  attribute vec2 pos;
+  varying vec4 radii;
+#else
+  in vec2 pos;
+  out vec4 radii;
+#endif
+
+void main() {
+	gl_Position = gl_ModelViewProjectionMatrix * vec4(pos, 0.0, 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 - outlineWidth;
+	radii[3] = radius - outlineWidth - 1.0;
+
+	// convert to PointCoord units
+	radii /= size;
+}

source/blender/gpu/shaders/gpu_shader_2D_point_uniform_size_uniform_color_smooth_vert.glsl

@@ -0,0 +1,25 @@
+
+uniform float size;
+
+#if __VERSION__ == 120
+  attribute vec2 pos;
+  varying vec2 radii;
+#else
+  in vec2 pos;
+  out vec2 radii;
+#endif
+
+void main() {
+	gl_Position = gl_ModelViewProjectionMatrix * vec4(pos, 0.0, 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;
+
+	// convert to PointCoord units
+	radii /= size;
+}

source/blender/gpu/shaders/gpu_shader_point_uniform_color_outline_smooth_frag.glsl

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+
+uniform vec4 color;
+uniform vec4 outlineColor;
+
+#if __VERSION__ == 120
+  varying vec4 radii;
+  #define fragColor gl_FragColor
+#else
+  in vec4 radii;
+  out vec4 fragColor;
+#endif
+
+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 = mix(outlineColor, vec4(0.0), smoothstep(radii[1], radii[0], dist));
+	else
+		fragColor = mix(color, outlineColor, smoothstep(radii[3], radii[2], dist));
+}

source/blender/gpu/shaders/gpu_shader_point_uniform_color_smooth_frag.glsl

@@ -0,0 +1,24 @@
+
+uniform vec4 color;
+
+#if __VERSION__ == 120
+  varying vec2 radii;
+  #define fragColor gl_FragColor
+#else
+  in vec2 radii;
+  out vec4 fragColor;
+#endif
+
+void main() {
+	float dist = length(gl_PointCoord - vec2(0.5));
+
+// transparent outside of point
+// --- 0 ---
+//	smooth transition
+// --- 1 ---
+// pure point color
+// ...
+// dist = 0 at center of point
+
+	fragColor = mix(color, vec4(0.0), smoothstep(radii[1], radii[0], dist));
+}