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First-pass fix for joints in 3d

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This commit is contained in:
Grant Sanderson
2023-01-10 15:17:08 -08:00
parent 131ecce7c4
commit 0c3367f27b
1 changed files with 51 additions and 30 deletions
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81
manimlib/shaders/quadratic_bezier_stroke/geom.glsl
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@ -50,16 +50,25 @@ const float ANGLE_THRESHOLD = 1e-3;
#INSERT get_gl_Position.glsl
#INSERT get_unit_normal.glsl
#INSERT finalize_color.glsl
#INSERT rotate.glsl
float angle_between(vec2 v1, vec2 v2){
float abs_angle = acos(clamp(dot(normalize(v1), normalize(v2)), -1.0, 1.0));
float sgn = sign(cross2d(v1, v2));
return sgn * abs_angle;
}
void create_joint(float angle, vec2 unit_tan, float buff,
vec2 static_c0, out vec2 changing_c0,
vec2 static_c1, out vec2 changing_c1){
float shift;
if(abs(angle) < ANGLE_THRESHOLD || int(joint_type) == NO_JOINT){
if(abs(angle) < ANGLE_THRESHOLD || abs(angle) > 0.99 * PI || int(joint_type) == NO_JOINT){
// No joint
shift = 0;
}else if(int(joint_type) == MITER_JOINT || (int(joint_type) == AUTO_JOINT && angle > 0.9 * PI)){
// }else if(int(joint_type) == MITER_JOINT || (int(joint_type) == AUTO_JOINT && abs(angle) > 0.95 * PI)){
}else if(int(joint_type) == MITER_JOINT){
shift = buff * (-1.0 - cos(angle)) / sin(angle);
}else{
// For a Bevel joint
@ -94,9 +103,16 @@ int get_corners(
vec2 p0_perp = sgn * vec2(-v01.y, v01.x); // Pointing to the inside of the curve from p0
vec2 p2_perp = sgn * vec2(-v12.y, v12.x); // Pointing to the inside of the curve from p2
// aaw is the added width given around the polygon for antialiasing.
// In case the normal is faced away from (0, 0, 1), the vector to the
// camera, this is scaled up.
// This is to prevent weird bevel artifacts for sharp angles
if(abs(angle_from_prev) > 0.5 * PI){
stroke_widths[0] *= sin(angle_from_prev);
stroke_widths[1] = 0.5 * (stroke_widths[0] + stroke_widths[2]);
}
if(abs(angle_to_next) > 0.5 * PI){
stroke_widths[2] *= sin(angle_to_next);
stroke_widths[1] = 0.5 * (stroke_widths[0] + stroke_widths[2]);
}
float buff0 = 0.5 * stroke_widths[0] + aaw;
float buff2 = 0.5 * stroke_widths[2] + aaw;
@ -127,23 +143,15 @@ void main() {
vec3 unit_normal = camera_rotation * vec3(0.0, 0.0, 1.0); // TODO, track true unit normal globally
// Control points are projected to the xy plane before drawing, which in turn
// gets tranlated to a uv plane. The z-coordinate information will be remembered
// by what's sent out to gl_Position, and by how it affects the lighting and stroke width
vec2 flat_controls[3];
float scaled_strokes[3];
for(int i = 0; i < 3; i++){
float sf = perspective_scale_factor(verts[i].z, focal_distance);
flat_controls[i] = sf * verts[i].xy;
scaled_strokes[i] = v_stroke_width[i];
if(bool(flat_stroke)){
vec3 to_cam = normalize(vec3(0.0, 0.0, focal_distance) - verts[i]);
sf *= abs(dot(unit_normal, to_cam));
scaled_strokes[i] *= abs(dot(unit_normal, to_cam));
}
scaled_strokes[i] = v_stroke_width[i] * sf;
}
// Set joint information
float angle_from_prev = v_joint_angle[0];
float angle_to_next = v_joint_angle[2];
@ -155,28 +163,44 @@ void main() {
// TODO, add anti-aliasing patch to curve end
angle_to_next = 0.0;
}
// Recompute angles based on perspective
if(angle_from_prev > 0.0 && unit_normal != vec3(0.0, 0.0, 1.0)){
vec3 v01 = verts[1] - verts[0];
vec3 from_prev = rotate(v01, angle_from_prev, unit_normal);
angle_from_prev = angle_between(from_prev.xy, v01.xy);
}
if(angle_to_next > 0.0 && unit_normal != vec3(0.0, 0.0, 1.0)){
vec3 v12 = verts[2] - verts[1];
vec3 to_next = rotate(v12, -angle_to_next, unit_normal);
angle_to_next = angle_between(v12.xy, to_next.xy);
}
// Control points are projected to the xy plane before drawing, which in turn
// gets tranlated to a uv plane. The z-coordinate information will be remembered
// by what's sent out to gl_Position, and by how it affects the lighting and stroke width
vec2 flat_verts[3] = vec2[3](verts[0].xy, verts[1].xy, verts[2].xy);
// If the curve is flat, put the middle control in the midpoint
is_linear = float(abs(v_joint_angle[1]) < ANGLE_THRESHOLD);
if (bool(is_linear)){
flat_verts[1] = 0.5 * (flat_verts[0] + flat_verts[2]);
}
// We want to change the coordinates to a space where the curve
// coincides with y = x^2, between some values x0 and x2. Or, in
// the case of a linear curve (bezier degree 1), just put it on
// the segment from (0, 0) to (1, 0)
is_linear = float(abs(v_joint_angle[1]) < ANGLE_THRESHOLD);
mat3 xy_to_uv = get_xy_to_uv(flat_controls, is_linear, is_linear);
mat3 xy_to_uv = get_xy_to_uv(flat_verts, is_linear, is_linear);
float uv_scale_factor = length(xy_to_uv[0].xy);
float scaled_anti_alias_width = anti_alias_width * (frame_shape.y / pixel_shape.y);
uv_anti_alias_width = uv_scale_factor * scaled_anti_alias_width;
// If the curve is flat, put the middle control in the midpoint
if (bool(is_linear)){
flat_controls[1] = 0.5 * (flat_controls[0] + flat_controls[2]);
}
float scaled_aaw = anti_alias_width * (frame_shape.y / pixel_shape.y);
uv_anti_alias_width = uv_scale_factor * scaled_aaw;
// Corners of a bounding region around curve
vec2 corners[5];
int n_corners = get_corners(
flat_controls, scaled_strokes,
scaled_anti_alias_width, angle_from_prev, angle_to_next,
flat_verts, scaled_strokes, scaled_aaw,
angle_from_prev, angle_to_next,
corners
);
@ -199,10 +223,7 @@ void main() {
gloss,
shadow
);
gl_Position = vec4(
get_gl_Position(vec3(corners[i], 0.0)).xy,
get_gl_Position(verts[index_map[i]]).zw
);
gl_Position = get_gl_Position(vec3(corners[i], verts[index_map[i]].z));
EmitVertex();
}
EndPrimitive();