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Small refactor to stroke geom shader

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This commit is contained in:
Grant Sanderson 2023-01-27 10:48:06 -08:00
parent 3a0916fe3a
commit 1c432dd6dc
1 changed files with 42 additions and 42 deletions
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84
manimlib/shaders/quadratic_bezier_stroke/geom.glsl
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@ -49,6 +49,12 @@ vec3 get_joint_unit_normal(vec4 joint_product){
} }
vec4 normalized_joint_product(vec4 joint_product){
float norm = length(joint_product);
return (norm > 1e-10) ? joint_product / norm : vec4(0.0, 0.0, 0.0, 1.0);
}
void create_joint( void create_joint(
vec4 joint_product, vec4 joint_product,
vec3 unit_tan, vec3 unit_tan,
@ -78,6 +84,25 @@ void create_joint(
changing_c1 = static_c1 + shift * unit_tan; changing_c1 = static_c1 + shift * unit_tan;
} }
vec3 get_perp(int index, vec4 joint_product, vec3 point, vec3 tangent, float aaw){
/*
Perpendicular vectors to the left of the curve
*/
float buff = 0.5 * v_stroke_width[index] + aaw;
// Add correction for sharp angles to prevent weird bevel effects
if(joint_product.w < -0.9) buff *= 10 * (joint_product.w + 1.0);
vec3 normal = get_joint_unit_normal(joint_product);
// Set global unit normal
unit_normal = normal;
// Choose the "outward" normal direction
if(normal.z < 0) normal *= -1;
if(bool(flat_stroke)){
return buff * normalize(cross(normal, tangent));
}else{
return buff * normalize(cross(camera_position - point, tangent));
}
}
// This function is responsible for finding the corners of // This function is responsible for finding the corners of
// a bounding region around the bezier curve, which can be // a bounding region around the bezier curve, which can be
// emitted as a triangle fan, with vertices vaguely close // emitted as a triangle fan, with vertices vaguely close
@ -95,40 +120,15 @@ void get_corners(
float aaw, float aaw,
out vec3 corners[6] out vec3 corners[6]
){ ){
bool linear = bool(is_linear);
float buff0 = 0.5 * v_stroke_width[0] + aaw; vec4 jp0 = normalized_joint_product(v_joint_product[0]);
float buff2 = 0.5 * v_stroke_width[2] + aaw; vec4 jp2 = normalized_joint_product(v_joint_product[2]);
vec3 p0_perp = get_perp(0, jp0, p0, v01, aaw);
vec4 jp0 = normalize(v_joint_product[0]); vec3 p2_perp = get_perp(2, jp2, p2, v12, aaw);
vec4 jp2 = normalize(v_joint_product[2]);
// Add correction for sharp angles to prevent weird bevel effects
if(jp0.w < -0.9) buff0 *= 10 * (jp0.w + 1.0);
if(jp2.w < -0.9) buff2 *= 10 * (jp2.w + 1.0);
// Unit normal and joint angles
vec3 normal0 = get_joint_unit_normal(jp0);
vec3 normal2 = get_joint_unit_normal(jp2);
// Set global unit normal
unit_normal = normal0;
// Choose the "outward" normal direction
normal0 *= sign(normal0.z);
normal2 *= sign(normal2.z);
vec3 p0_perp;
vec3 p2_perp;
if(bool(flat_stroke)){
// Perpendicular vectors to the left of the curve
p0_perp = buff0 * normalize(cross(normal0, v01));
p2_perp = buff2 * normalize(cross(normal2, v12));
}else{
// p0_perp = buff0 * normal0;
// p2_perp = buff2 * normal2;
p0_perp = buff0 * normalize(cross(camera_position - p0, v01));
p2_perp = buff2 * normalize(cross(camera_position - p2, v12));
}
vec3 p1_perp = 0.5 * (p0_perp + p2_perp); vec3 p1_perp = 0.5 * (p0_perp + p2_perp);
if(linear){
p1_perp *= (0.5 * v_stroke_width[1] + aaw) / length(p1_perp);
}
// The order of corners should be for a triangle_strip. // The order of corners should be for a triangle_strip.
vec3 c0 = p0 + p0_perp; vec3 c0 = p0 + p0_perp;
@ -139,14 +139,15 @@ void get_corners(
vec3 c5 = p2 - p2_perp; vec3 c5 = p2 - p2_perp;
// Move the inner middle control point to make // Move the inner middle control point to make
// room for the curve // room for the curve
float orientation = dot(normal0, v_joint_product[1].xyz); // float orientation = dot(unit_normal, v_joint_product[1].xyz);
if(orientation >= 0.0) c2 = 0.5 * (c0 + c4); float orientation = v_joint_product[1].z;
else if(orientation < 0.0) c3 = 0.5 * (c1 + c5); if(!linear && orientation >= 0.0) c2 = 0.5 * (c0 + c4);
else if(!linear && orientation < 0.0) c3 = 0.5 * (c1 + c5);
// Account for previous and next control points // Account for previous and next control points
if(bool(flat_stroke)){ if(bool(flat_stroke)){
create_joint(jp0, v01, buff0, c1, c1, c0, c0); create_joint(jp0, v01, length(p0_perp), c1, c1, c0, c0);
create_joint(jp2, -v12, buff2, c5, c5, c4, c4); create_joint(jp2, -v12, length(p2_perp), c5, c5, c4, c4);
} }
corners = vec3[6](c0, c1, c2, c3, c4, c5); corners = vec3[6](c0, c1, c2, c3, c4, c5);
@ -167,10 +168,9 @@ void main() {
vec3 v01 = normalize(p1 - p0); vec3 v01 = normalize(p1 - p0);
vec3 v12 = normalize(p2 - p1); vec3 v12 = normalize(p2 - p1);
vec4 jp1 = v_joint_product[1];
float norm = length(jp1); vec4 jp1 = normalized_joint_product(v_joint_product[1]);
float cos_angle = (norm > 0) ? (jp1 / norm).w : 1.0; is_linear = float(jp1.w > COS_THRESHOLD);
is_linear = float(cos_angle > COS_THRESHOLD);
// We want to change the coordinates to a space where the curve // 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 // coincides with y = x^2, between some values x0 and x2. Or, in