Realtime Compositor: Add basic matte nodes

This patch implements the following nodes for the realtime compositor:

- Box mask node.
- Channel matte node.
- Chroma matte node.
- Color matte node.
- Color spill node.
- Difference matte node.
- Distance matte node.
- Ellipse matte node.
- Luminance matte node.

Differential Revision: https://developer.blender.org/D15230

Reviewed By: Clement Foucault

7 files changed, 185 insertions, 0 deletions

diff --git a/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_channel_matte.glsl b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_channel_matte.glsl
new file mode 100644
index 00000000000..f2dcc9543f2
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_channel_matte.glsl
@@ -0,0 +1,52 @@
+#pragma BLENDER_REQUIRE(gpu_shader_common_color_utils.glsl)
+
+#define CMP_NODE_CHANNEL_MATTE_CS_RGB 1.0
+#define CMP_NODE_CHANNEL_MATTE_CS_HSV 2.0
+#define CMP_NODE_CHANNEL_MATTE_CS_YUV 3.0
+#define CMP_NODE_CHANNEL_MATTE_CS_YCC 4.0
+
+void node_composite_channel_matte(vec4 color,
+                                  const float color_space,
+                                  const float matte_channel,
+                                  const vec2 limit_channels,
+                                  float max_limit,
+                                  float min_limit,
+                                  out vec4 result,
+                                  out float matte)
+{
+  vec4 channels;
+  if (color_space == CMP_NODE_CHANNEL_MATTE_CS_HSV) {
+    rgb_to_hsv(color, channels);
+  }
+  else if (color_space == CMP_NODE_CHANNEL_MATTE_CS_YUV) {
+    rgba_to_yuva_itu_709(color, channels);
+  }
+  else if (color_space == CMP_NODE_CHANNEL_MATTE_CS_YCC) {
+    rgba_to_ycca_itu_709(color, channels);
+  }
+  else {
+    channels = color;
+  }
+
+  float matte_value = channels[int(matte_channel)];
+  float limit_value = max(channels[int(limit_channels.x)], channels[int(limit_channels.y)]);
+
+  float alpha = 1.0 - (matte_value - limit_value);
+  if (alpha > max_limit) {
+    alpha = color.a;
+  }
+  else if (alpha < min_limit) {
+    alpha = 0.0;
+  }
+  else {
+    alpha = (alpha - min_limit) / (max_limit - min_limit);
+  }
+
+  matte = min(alpha, color.a);
+  result = color * matte;
+}
+
+#undef CMP_NODE_CHANNEL_MATTE_CS_RGB
+#undef CMP_NODE_CHANNEL_MATTE_CS_HSV
+#undef CMP_NODE_CHANNEL_MATTE_CS_YUV
+#undef CMP_NODE_CHANNEL_MATTE_CS_YCC
diff --git a/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_chroma_matte.glsl b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_chroma_matte.glsl
new file mode 100644
index 00000000000..5d6bea0c9db
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_chroma_matte.glsl
@@ -0,0 +1,43 @@
+#pragma BLENDER_REQUIRE(gpu_shader_common_math_utils.glsl)
+#pragma BLENDER_REQUIRE(gpu_shader_common_color_utils.glsl)
+
+/* Algorithm from the book Video Demystified. Chapter 7. Chroma Keying. */
+void node_composite_chroma_matte(vec4 color,
+                                 vec4 key,
+                                 float acceptance,
+                                 float cutoff,
+                                 float falloff,
+                                 out vec4 result,
+                                 out float matte)
+{
+  vec4 color_ycca;
+  rgba_to_ycca_itu_709(color, color_ycca);
+  vec4 key_ycca;
+  rgba_to_ycca_itu_709(key, key_ycca);
+
+  /* Normalize the CrCb components into the [-1, 1] range. */
+  vec2 color_cc = color_ycca.yz * 2.0 - 1.0;
+  vec2 key_cc = key_ycca.yz * 2.0 - 1.0;
+
+  /* Rotate the color onto the space of the key such that x axis of the color space passes through
+   * the key color. */
+  color_cc = vector_to_rotation_matrix(key_cc * vec2(1.0, -1.0)) * color_cc;
+
+  /* Compute foreground key. If positive, the value is in the [0, 1] range. */
+  float foreground_key = color_cc.x - (abs(color_cc.y) / acceptance);
+
+  /* Negative foreground key values retain the original alpha. Positive values are scaled by the
+   * falloff, while colors that make an angle less than the cutoff angle get a zero alpha. */
+  float alpha = color.a;
+  if (foreground_key > 0.0) {
+    alpha = 1.0 - (foreground_key / falloff);
+
+    if (abs(atan(color_cc.y, color_cc.x)) < (cutoff / 2.0)) {
+      alpha = 0.0;
+    }
+  }
+
+  /* Compute output. */
+  matte = min(alpha, color.a);
+  result = color * matte;
+}
diff --git a/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_color_matte.glsl b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_color_matte.glsl
new file mode 100644
index 00000000000..038471bc1bc
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_color_matte.glsl
@@ -0,0 +1,27 @@
+#pragma BLENDER_REQUIRE(gpu_shader_common_color_utils.glsl)
+
+void node_composite_color_matte(vec4 color,
+                                vec4 key,
+                                float hue_epsilon,
+                                float saturation_epsilon,
+                                float value_epsilon,
+                                out vec4 result,
+                                out float matte)
+
+{
+  vec4 color_hsva;
+  rgb_to_hsv(color, color_hsva);
+  vec4 key_hsva;
+  rgb_to_hsv(key, key_hsva);
+
+  bool is_within_saturation = distance(color_hsva.y, key_hsva.y) < saturation_epsilon;
+  bool is_within_value = distance(color_hsva.z, key_hsva.z) < value_epsilon;
+  bool is_within_hue = distance(color_hsva.x, key_hsva.x) < hue_epsilon;
+  /* Hue wraps around, so check the distance around the boundary. */
+  float min_hue = min(color_hsva.x, key_hsva.x);
+  float max_hue = max(color_hsva.x, key_hsva.x);
+  is_within_hue = is_within_hue || ((min_hue + (1.0 - max_hue)) < hue_epsilon);
+
+  matte = (is_within_hue && is_within_saturation && is_within_value) ? 0.0 : color.a;
+  result = color * matte;
+}
diff --git a/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_color_spill.glsl b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_color_spill.glsl
new file mode 100644
index 00000000000..0adad53ad80
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_color_spill.glsl
@@ -0,0 +1,13 @@
+void node_composite_color_spill(vec4 color,
+                                float factor,
+                                const float spill_channel,
+                                vec3 spill_scale,
+                                const vec2 limit_channels,
+                                float limit_scale,
+                                out vec4 result)
+{
+  float average_limit = (color[int(limit_channels.x)] + color[int(limit_channels.y)]) / 2.0;
+  float map = factor * color[int(spill_channel)] - limit_scale * average_limit;
+  result.rgb = map > 0.0 ? color.rgb + spill_scale * map : color.rgb;
+  result.a = color.a;
+}
diff --git a/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_difference_matte.glsl b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_difference_matte.glsl
new file mode 100644
index 00000000000..d769cadce3c
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_difference_matte.glsl
@@ -0,0 +1,10 @@
+void node_composite_difference_matte(
+    vec4 color, vec4 key, float tolerance, float falloff, out vec4 result, out float matte)
+{
+  vec4 difference = abs(color - key);
+  float average_difference = (difference.r + difference.g + difference.b) / 3.0;
+  bool is_opaque = average_difference > tolerance + falloff;
+  float alpha = is_opaque ? color.a : (max(0.0, average_difference - tolerance) / falloff);
+  matte = min(alpha, color.a);
+  result = color * matte;
+}
diff --git a/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_distance_matte.glsl b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_distance_matte.glsl
new file mode 100644
index 00000000000..9beed66826c
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_distance_matte.glsl
@@ -0,0 +1,26 @@
+#pragma BLENDER_REQUIRE(gpu_shader_common_color_utils.glsl)
+
+void node_composite_distance_matte_rgba(
+    vec4 color, vec4 key, float tolerance, float falloff, out vec4 result, out float matte)
+{
+  float difference = distance(color.rgb, key.rgb);
+  bool is_opaque = difference > tolerance + falloff;
+  float alpha = is_opaque ? color.a : max(0.0, difference - tolerance) / falloff;
+  matte = min(alpha, color.a);
+  result = color * matte;
+}
+
+void node_composite_distance_matte_ycca(
+    vec4 color, vec4 key, float tolerance, float falloff, out vec4 result, out float matte)
+{
+  vec4 color_ycca;
+  rgba_to_ycca_itu_709(color, color_ycca);
+  vec4 key_ycca;
+  rgba_to_ycca_itu_709(key, key_ycca);
+
+  float difference = distance(color_ycca.yz, key_ycca.yz);
+  bool is_opaque = difference > tolerance + falloff;
+  float alpha = is_opaque ? color.a : max(0.0, difference - tolerance) / falloff;
+  matte = min(alpha, color.a);
+  result = color * matte;
+}
diff --git a/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_luminance_matte.glsl b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_luminance_matte.glsl
new file mode 100644
index 00000000000..3647ac583fe
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_luminance_matte.glsl
@@ -0,0 +1,14 @@
+#pragma BLENDER_REQUIRE(gpu_shader_common_color_utils.glsl)
+
+void node_composite_luminance_matte(vec4 color,
+                                    float high,
+                                    float low,
+                                    const vec3 luminance_coefficients,
+                                    out vec4 result,
+                                    out float matte)
+{
+  float luminance = get_luminance(color.rgb, luminance_coefficients);
+  float alpha = clamp(0.0, 1.0, (luminance - low) / (high - low));
+  matte = min(alpha, color.a);
+  result = color * matte;
+}