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Update fill shader alpha blending, and simplify the fill canvas

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This commit is contained in:
Grant Sanderson
2023-02-02 10:42:24 -08:00
parent 0cf9a35367
commit c3823e722d
3 changed files with 14 additions and 33 deletions
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33
manimlib/utils/shaders.py
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@ -103,7 +103,7 @@ def get_colormap_code(rgb_list: Sequence[float]) -> str:
@lru_cache()
def get_fill_canvas(ctx: moderngl.Context) -> Tuple[Framebuffer, VertexArray, Tuple[float, float, float]]:
def get_fill_canvas(ctx: moderngl.Context) -> Tuple[Framebuffer, VertexArray]:
"""
Because VMobjects with fill are rendered in a funny way, using
alpha blending to effectively compute the winding number around
@ -123,26 +123,16 @@ def get_fill_canvas(ctx: moderngl.Context) -> Tuple[Framebuffer, VertexArray, Tu
depth_texture = ctx.depth_texture(size=size)
texture_fbo = ctx.framebuffer(texture, depth_texture)
# We'll paint onto a canvas with initially negative rgbs, and
# discard any pixels remaining close to this value. This is
# because alphas are effectively being used for another purpose,
# and we don't want to overlap with any colors one might actually
# use. It should be negative enough to be distinguishable from
# ordinary colors with some margin, but the farther it's pulled back
# from zero the more it will be true that overlapping filled objects
# with transparency have an unnaturally bright composition.
null_rgb = (-0.25, -0.25, -0.25)
simple_program = ctx.program(
vertex_shader='''
#version 330
in vec2 texcoord;
out vec2 v_textcoord;
out vec2 uv;
void main() {
gl_Position = vec4((2.0 * texcoord - 1.0), 0.0, 1.0);
v_textcoord = texcoord;
uv = texcoord;
}
''',
fragment_shader='''
@ -150,31 +140,24 @@ def get_fill_canvas(ctx: moderngl.Context) -> Tuple[Framebuffer, VertexArray, Tu
uniform sampler2D Texture;
uniform sampler2D DepthTexture;
uniform vec3 null_rgb;
in vec2 v_textcoord;
in vec2 uv;
out vec4 color;
const float MIN_DIST_TO_NULL = 0.2;
void main() {
color = texture(Texture, v_textcoord);
color = texture(Texture, uv);
if(color.a == 0) discard;
if(distance(color.rgb, null_rgb) < MIN_DIST_TO_NULL) discard;
// Un-blend from the null value
color.rgb -= (1 - color.a) * null_rgb;
// Counteract scaling in fill frag
color.a *= 1.01;
color.a *= 1.06;
gl_FragDepth = texture(DepthTexture, v_textcoord)[0];
gl_FragDepth = texture(DepthTexture, uv)[0];
}
''',
)
simple_program['Texture'].value = get_texture_id(texture)
simple_program['DepthTexture'].value = get_texture_id(depth_texture)
simple_program['null_rgb'].value = null_rgb
verts = np.array([[0, 0], [0, 1], [1, 0], [1, 1]])
fill_texture_vao = ctx.simple_vertex_array(
@ -183,4 +166,4 @@ def get_fill_canvas(ctx: moderngl.Context) -> Tuple[Framebuffer, VertexArray, Tu
'texcoord',
mode=moderngl.TRIANGLE_STRIP
)
return (texture_fbo, fill_texture_vao, null_rgb)
return (texture_fbo, fill_texture_vao)