68 lines
1.9 KiB
Python
68 lines
1.9 KiB
Python
"""
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Custom Shader for dotted 3D Line
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--------------------------------
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In this example the arc length (distance to the first point on the line) is calculated in every vertex.
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Between the vertex and fragment shader that value is automatically interpolated
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for all points that will be visible on the screen.
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In the fragment shader the ``sin`` of the arc length is calculated.
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Based on the result a decision is made on whether the fragment should be drawn or not.
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"""
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import bpy
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import gpu
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from random import random
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from mathutils import Vector
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from gpu_extras.batch import batch_for_shader
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vert_out = gpu.types.GPUStageInterfaceInfo("my_interface")
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vert_out.smooth('FLOAT', "v_ArcLength")
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shader_info = gpu.types.GPUShaderCreateInfo()
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shader_info.push_constant('MAT4', "u_ViewProjectionMatrix")
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shader_info.push_constant('FLOAT', "u_Scale")
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shader_info.vertex_in(0, 'VEC3', "position")
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shader_info.vertex_in(1, 'FLOAT', "arcLength")
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shader_info.vertex_out(vert_out)
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shader_info.fragment_out(0, 'VEC4', "FragColor")
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shader_info.vertex_source(
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"void main()"
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"{"
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" v_ArcLength = arcLength;"
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" gl_Position = u_ViewProjectionMatrix * vec4(position, 1.0f);"
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"}"
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)
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shader_info.fragment_source(
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"void main()"
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"{"
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" if (step(sin(v_ArcLength * u_Scale), 0.5) == 1) discard;"
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" FragColor = vec4(1.0);"
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"}"
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)
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shader = gpu.shader.create_from_info(shader_info)
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del vert_out
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del shader_info
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coords = [Vector((random(), random(), random())) * 5 for _ in range(5)]
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arc_lengths = [0]
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for a, b in zip(coords[:-1], coords[1:]):
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arc_lengths.append(arc_lengths[-1] + (a - b).length)
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batch = batch_for_shader(
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shader, 'LINE_STRIP',
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{"position": coords, "arcLength": arc_lengths},
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)
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def draw():
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matrix = bpy.context.region_data.perspective_matrix
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shader.uniform_float("u_ViewProjectionMatrix", matrix)
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shader.uniform_float("u_Scale", 10)
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batch.draw(shader)
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bpy.types.SpaceView3D.draw_handler_add(draw, (), 'WINDOW', 'POST_VIEW')
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