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#version 330
#if defined VERTEX_SHADER
in vec3 in_position;
in vec2 in_texcoord_0;
out vec2 uv0;
void main() {
gl_Position = vec4(in_position, 1);
uv0 = in_texcoord_0;
}
#elif defined FRAGMENT_SHADER
out float fragColor;
in vec2 uv0;
uniform sampler2D momentum_texture;
uniform sampler2D pressure_texture;
uniform sampler2D walls_texture;
uniform float rho;
uniform float damping;
uniform float external_flow;
const ivec2 kpos[9] = ivec2[9](
ivec2(-1, 1), ivec2(0, 1), ivec2(1, 1),
ivec2(-1, 0), ivec2(0, 0), ivec2(1, 0),
ivec2(-1, -1), ivec2(0, -1), ivec2(1, -1)
);
const float diff_kernel[9] = float[9](
.025, .1, .025,
.1, .5, .1,
.025, .1, .025
);
const float con_kernel[9] = float[9](
0.0, .25, 0.0,
.25, -1.0, .25,
0.0, .25, 0.0
);
float diffusion(ivec2 uv, sampler2D source) {
float value = 0;
for (int i = 0; i < 9; i++) {
value += texelFetch(source, uv + kpos[i], 0).r * diff_kernel[i];
}
return value;
}
const float viscosity = .018;
float convection(ivec2 uv, sampler2D source) {
float value = 0;
for (int i = 0; i < 9; i++) {
value += texelFetch(source, uv + kpos[i], 0).r * con_kernel[i];
}
return value;
}
void main() {
ivec2 uv = ivec2(gl_FragCoord.xy);
float momentum = texelFetch(momentum_texture, uv, 0).r;
float wall = texelFetch(walls_texture, uv, 0).r;
float diff_momentum = diffusion(uv, momentum_texture);
float con_momentum = convection(uv, momentum_texture);
float con_pressure = convection(uv, pressure_texture);
if (wall > 0) {
fragColor = -external_flow;
} else {
fragColor = (diff_momentum -
viscosity * momentum *
con_momentum +
con_pressure * rho) * damping;
}
}
#endif
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