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/* Infinite grid
* Clément Foucault */
out vec4 FragColor;
uniform mat4 ProjectionMatrix;
uniform vec3 cameraPos;
uniform vec3 planeNormal;
uniform vec3 planeAxes;
uniform vec3 eye;
uniform vec4 gridSettings;
uniform vec2 viewportSize;
uniform vec4 screenvecs[3];
uniform float gridOneOverLogSubdiv;
#define gridDistance gridSettings.x
#define gridResolution gridSettings.y
#define gridScale gridSettings.z
#define gridSubdiv gridSettings.w
uniform int gridFlag;
#define AXIS_X (1 << 0)
#define AXIS_Y (1 << 1)
#define AXIS_Z (1 << 2)
#define GRID (1 << 3)
#define PLANE_XY (1 << 4)
#define PLANE_XZ (1 << 5)
#define PLANE_YZ (1 << 6)
#define GRID_LINE_SMOOTH 1.15
float get_grid(vec3 co, vec3 fwidthCos, float grid_size)
{
float half_size = grid_size / 2.0;
/* triangular wave pattern, amplitude is [0, grid_size] */
vec3 grid_domain = abs(mod(co + half_size, grid_size) - half_size);
/* modulate by the absolute rate of change of the coordinates
* (make lines have the same width under perspective) */
grid_domain /= fwidthCos;
/* collapse waves and normalize */
grid_domain.x = min(grid_domain.x, min(grid_domain.y, grid_domain.z)) / grid_size;
return 1.0 - smoothstep(0.0, GRID_LINE_SMOOTH / grid_size, grid_domain.x);
}
vec3 get_axes(vec3 co, vec3 fwidthCos, float line_size)
{
vec3 axes_domain = abs(co);
/* modulate by the absolute rate of change of the coordinates
* (make line have the same width under perspective) */
axes_domain /= fwidthCos;
return 1.0 - smoothstep(0.0, GRID_LINE_SMOOTH, axes_domain - line_size);
}
vec3 get_floor_pos(vec2 uv, out vec3 wPos)
{
vec3 camera_vec, camera_pos, corner_pos;
vec3 floored_pos = planeAxes * floor(screenvecs[2].xyz);
corner_pos = screenvecs[2].xyz - floored_pos;
vec3 pixel_pos = corner_pos + uv.x * screenvecs[0].xyz + uv.y * screenvecs[1].xyz;
/* if perspective */
if (ProjectionMatrix[3][3] == 0.0) {
camera_pos = cameraPos - floored_pos;
camera_vec = normalize(pixel_pos - camera_pos);
}
else {
camera_pos = pixel_pos;
camera_vec = normalize(eye);
}
float p = -dot(planeNormal, camera_pos) / dot(planeNormal, camera_vec);
vec3 plane = camera_pos + camera_vec * p;
/* fix residual imprecision */
plane *= planeAxes;
/* Recover non-offseted world position */
wPos = plane + floored_pos;
return plane;
}
void main()
{
vec2 sPos = gl_FragCoord.xy / viewportSize; /* Screen [0,1] position */
/* To reduce artifacts, use a local version of the positions
* to compute derivatives since they are not position dependant.
* This gets rid of the blocky artifacts. Unfortunately we still
* need the world position for the grid to scale properly from the origin. */
vec3 gPos, wPos; /* Grid pos., World pos. */
gPos = get_floor_pos(sPos, wPos);
vec3 fwidthPos = fwidth(gPos);
float dist, fade;
/* if persp */
if (ProjectionMatrix[3][3] == 0.0) {
vec3 viewvec = cameraPos - wPos;
dist = length(viewvec);
viewvec /= dist;
float angle;
if ((gridFlag & PLANE_XZ) > 0)
angle = viewvec.y;
else if ((gridFlag & PLANE_YZ) > 0)
angle = viewvec.x;
else
angle = viewvec.z;
angle = 1.0 - abs(angle);
fade = 1.0 - angle * angle;
fade *= 1.0 - smoothstep(0.0, gridDistance, dist - gridDistance);
}
else {
dist = abs(gl_FragCoord.z * 2.0 - 1.0);
fade = 1.0 - smoothstep(0.0, 0.5, dist - 0.5);
dist = 1.0; /* avoid branch after */
if ((gridFlag & PLANE_XY) > 0) {
float angle = 1.0 - abs(eye.z);
fade *= 1.0 - angle * angle * angle;
dist = 1.0 + angle * 2.0;
}
}
if ((gridFlag & GRID) > 0) {
float grid_res = log(dist * gridResolution) * gridOneOverLogSubdiv;
float blend = fract(-max(grid_res, 0.0));
float lvl = floor(grid_res);
/* from biggest to smallest */
float scaleA = gridScale * pow(gridSubdiv, max(lvl - 1.0, 0.0));
float scaleB = gridScale * pow(gridSubdiv, max(lvl + 0.0, 0.0));
float scaleC = gridScale * pow(gridSubdiv, max(lvl + 1.0, 1.0));
float gridA = get_grid(wPos, fwidthPos, scaleA);
float gridB = get_grid(wPos, fwidthPos, scaleB);
float gridC = get_grid(wPos, fwidthPos, scaleC);
FragColor = vec4(colorGrid.rgb, gridA * blend);
FragColor = mix(FragColor, vec4(mix(colorGrid.rgb, colorGridEmphasise.rgb, blend), 1.0), gridB);
FragColor = mix(FragColor, vec4(colorGridEmphasise.rgb, 1.0), gridC);
}
else {
FragColor = vec4(colorGrid.rgb, 0.0);
}
if ((gridFlag & (AXIS_X | AXIS_Y | AXIS_Z)) > 0) {
/* Setup axes 'domains' */
vec3 axes_dist, axes_fwidth;
if ((gridFlag & AXIS_X) > 0) {
axes_dist.x = dot(wPos.yz, planeAxes.yz);
axes_fwidth.x = dot(fwidthPos.yz, planeAxes.yz);
}
if ((gridFlag & AXIS_Y) > 0) {
axes_dist.y = dot(wPos.xz, planeAxes.xz);
axes_fwidth.y = dot(fwidthPos.xz, planeAxes.xz);
}
if ((gridFlag & AXIS_Z) > 0) {
axes_dist.z = dot(wPos.xy, planeAxes.xy);
axes_fwidth.z = dot(fwidthPos.xy, planeAxes.xy);
}
/* Computing all axes at once using vec3 */
vec3 axes = get_axes(axes_dist, axes_fwidth, 0.1);
if ((gridFlag & AXIS_X) > 0) {
FragColor = mix(FragColor, colorGridAxisX, axes.x);
}
if ((gridFlag & AXIS_Y) > 0) {
FragColor = mix(FragColor, colorGridAxisY, axes.y);
}
if ((gridFlag & AXIS_Z) > 0) {
FragColor = mix(FragColor, colorGridAxisZ, axes.z);
}
}
FragColor.a *= fade;
}
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