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'''
This examples renders 8 clones of a rectangle with different sizes and positions
and having the same color
'''
import numpy as np
from _example import Example
class InstancedRendering(Example):
gl_version = (3, 3)
title = "Instanced Rendering"
aspect_ratio = 1.0
window_size = (640, 640)
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.prog = self.ctx.program(
vertex_shader='''
#version 330
in vec2 in_vert;
in vec2 in_pos;
in float in_scale;
in vec3 in_color;
out vec3 v_color;
void main() {
gl_Position = vec4(in_pos + (in_vert * in_scale), 0.0, 1.0);
v_color = in_color;
}
''',
fragment_shader='''
#version 330
in vec3 v_color;
out vec4 f_color;
void main() {
f_color = vec4(v_color, 1.0);
}
''',
)
# Vertex coordinates stored in position_vertex_buffer
#
# B------D
# | |
# A------C
vertices = np.array([
-0.5, -0.5,
-0.5, 0.5,
0.5, -0.5,
0.5, 0.5,
])
self.position_vertex_buffer = self.ctx.buffer(vertices.astype('f4'))
# Vertex colors stored in color_buffer
#
# A, B are green
# C, D are blue
colors = np.array([
0.0, 1.0, 0.0,
0.0, 1.0, 0.0,
0.0, 0.0, 1.0,
0.0, 0.0, 1.0,
])
self.color_buffer = self.ctx.buffer(colors.astype('f4'))
# (Per instance) positions and scales stored in pos_scale_buffer
# There are 8 (x_position, y_position, scale) pairs
position_scale = np.array([
0.5, 0.0, 0.3,
0.35, 0.35, 0.2,
0.0, 0.5, 0.3,
-0.35, 0.35, 0.2,
-0.5, 0.0, 0.3,
-0.35, -0.35, 0.2,
0.0, -0.5, 0.3,
0.35, -0.35, 0.2,
])
self.pos_scale_buffer = self.ctx.buffer(position_scale.astype('f4'))
# Index buffer (also called element buffer)
# There are 2 trianges to render
#
# A, B, C
# B, C, D
render_indicies = np.array([
0, 1, 2,
1, 2, 3
])
self.index_buffer = self.ctx.buffer(render_indicies.astype('i4'))
# The vao_content is a list of 3-tuples (buffer, format, attribs)
# the format can have an empty or '/v', '/i', '/r' ending.
# '/v' attributes are the default
# '/i` attributes are per instance attributes
# '/r' attributes are default values for the attributes (per render attributes)
vao_content = [
(self.position_vertex_buffer, '2f', 'in_vert'),
(self.color_buffer, '3f', 'in_color'),
(self.pos_scale_buffer, '2f 1f/i', 'in_pos', 'in_scale'),
]
self.vao = self.ctx.vertex_array(self.prog, vao_content, self.index_buffer)
def render(self, time: float, frame_time: float):
self.ctx.clear(1.0, 1.0, 1.0)
self.vao.render(instances=8)
if __name__ == '__main__':
InstancedRendering.run()
|
