ComputeShaderPerformance2.py

from panda3d.core import *

loadPrcFileData("","""

show-frame-rate-meter #t

""".strip())
from direct.directbase import DirectStart
import math

# Shader
compute_source = """#version 430
#pragma optionNV (unroll all)
layout (rgba8) uniform image2D destTex;
layout (local_size_x = 32, local_size_y = 32) in;

uniform float test;

void main() {
    vec4 result = vec4(0, 0, 0, 1);
    float minDepth = test;
    
    for (int i = 0; i < 2000; i ++) {
        minDepth += sin(float(i+minDepth));
    }

    ivec2 storePos = ivec2(gl_GlobalInvocationID.xy);
    imageStore(destTex, storePos, vec4(minDepth));

}"""

# Create shader / compute node
shader = Shader.make_compute(Shader.SL_GLSL, compute_source)
compute_node = ComputeNode('compute')
compute_node.add_dispatch(1600/32, 960/32, 1)
tex = Texture()

# Create destination tex
tex.setup_2d_texture(1600, 960, Texture.TFloat, Texture.FRgba8)
tex.set_format(Texture.F_rgba8)
tex.set_minfilter(Texture.FT_nearest)
tex.set_magfilter(Texture.FT_nearest)

# Attach compute node and set shader inputs
np = render.attach_new_node(compute_node)
np.set_shader(shader)
np.set_shader_input('destTex', tex)
np.set_shader_input('test', 0.123123) # prevent unrolling

# Create card to show texture
cm = CardMaker('card')
cm.set_frame_fullscreen_quad()
card = render2d.attach_new_node(cm.generate())
card.set_texture(tex)

# Done!
run()