New tech ENABLE_SLOPE_RENDERING - 1st installment of rendering objects colored by facets slope

2 files changed, 38 insertions, 4 deletions

diff --git a/resources/shaders/gouraud.fs b/resources/shaders/gouraud.fs
index 09003f407..be75b7d9a 100644
--- a/resources/shaders/gouraud.fs
+++ b/resources/shaders/gouraud.fs
@@ -1,6 +1,21 @@
 #version 110
 
 const vec3 ZERO = vec3(0.0, 0.0, 0.0);
+const vec3 GREEN = vec3(0.0, 0.65, 0.0);
+const vec3 YELLOW = vec3(0.5, 0.65, 0.0);
+const vec3 RED = vec3(0.65, 0.0, 0.0);
+const float EPSILON = 0.0001;
+
+struct SlopeDetection
+{
+    bool active;
+	// x = yellow z, y = red z
+	vec2 z_range;
+    mat3 volume_world_normal_matrix;
+};
+
+uniform vec4 uniform_color;
+uniform SlopeDetection slope;
 
 varying vec3 clipping_planes_dots;
 
@@ -10,14 +25,19 @@ varying vec2 intensity;
 varying vec3 delta_box_min;
 varying vec3 delta_box_max;
 
-uniform vec4 uniform_color;
+varying float world_normal_z;
 
+vec3 slope_color()
+{
+    return (world_normal_z > slope.z_range.x - EPSILON) ? GREEN : mix(RED, YELLOW, (world_normal_z - slope.z_range.y) / (slope.z_range.x - slope.z_range.y));
+}
 
 void main()
 {
     if (any(lessThan(clipping_planes_dots, ZERO)))
         discard;
+	vec3 color = slope.active ? slope_color() : uniform_color.rgb;
     // if the fragment is outside the print volume -> use darker color
-    vec3 color = (any(lessThan(delta_box_min, ZERO)) || any(greaterThan(delta_box_max, ZERO))) ? mix(uniform_color.rgb, ZERO, 0.3333) : uniform_color.rgb;
+	color = (any(lessThan(delta_box_min, ZERO)) || any(greaterThan(delta_box_max, ZERO))) ? mix(color, ZERO, 0.3333) : color;
     gl_FragColor = vec4(vec3(intensity.y, intensity.y, intensity.y) + color * intensity.x, uniform_color.a);
 }
diff --git a/resources/shaders/gouraud.vs b/resources/shaders/gouraud.vs
index cc54c1c44..3c06729f8 100644
--- a/resources/shaders/gouraud.vs
+++ b/resources/shaders/gouraud.vs
@@ -20,13 +20,22 @@ const vec3 ZERO = vec3(0.0, 0.0, 0.0);
 
 struct PrintBoxDetection
 {
+    bool active;
     vec3 min;
     vec3 max;
-    bool volume_detection;
     mat4 volume_world_matrix;
 };
 
+struct SlopeDetection
+{
+    bool active;
+	// x = yellow z, y = red z
+	vec2 z_range;
+    mat3 volume_world_normal_matrix;
+};
+
 uniform PrintBoxDetection print_box;
+uniform SlopeDetection slope;
 
 // Clipping plane, x = min z, y = max z. Used by the FFF and SLA previews to clip with a top / bottom plane.
 uniform vec2 z_range;
@@ -41,6 +50,8 @@ varying vec3 delta_box_max;
 
 varying vec3 clipping_planes_dots;
 
+varying float world_normal_z;
+
 void main()
 {
     // First transform the normal into camera space and normalize the result.
@@ -61,7 +72,7 @@ void main()
     intensity.x += NdotL * LIGHT_FRONT_DIFFUSE;
 
     // compute deltas for out of print volume detection (world coordinates)
-    if (print_box.volume_detection)
+    if (print_box.active)
     {
         vec3 v = (print_box.volume_world_matrix * gl_Vertex).xyz;
         delta_box_min = v - print_box.min;
@@ -73,6 +84,9 @@ void main()
         delta_box_max = ZERO;
     }
 
+    // z component of normal vector in world coordinate used for slope shading
+	world_normal_z = slope.active ? (normalize(slope.volume_world_normal_matrix * gl_Normal)).z : 0.0;
+
     gl_Position = ftransform();
     // Point in homogenous coordinates.
     vec4 world_pos = print_box.volume_world_matrix * gl_Vertex;