Splat¶
This example renders Gaussian splats as translucent ellipses.
Preview¶
Run And Adapt¶
Commands below assume a Datoviz source checkout and start at the repository root. Use your configured build environment; Python routes additionally require local bindings.
| Route | Availability | Command or action |
|---|---|---|
| C | Canonical native source | just example-c visuals/splat (build and run), or rerun ./build/examples/c/visuals/splat |
| Python | No verified adaptation on this page | Start from the C source. |
| Browser | Deferred | splat rendering is experimental and outside the RC browser subset |
Use this example as capability or integration evidence, not as a minimal copy-paste template. Start from the nearest supported, copy-safe example and add this feature after verifying the linked API reference.
What To Look For¶
Positions place each splat, colors set the tint, sigma gives the two screen-space ellipse radii, and angles rotate the ellipses. Compare overlapping areas and the soft footprint shape to see how uncertain samples, local point spread, or projected density can be shown without drawing hard-edged markers.
Source¶
/*
* Copyright (c) 2021 Cyrille Rossant and contributors. All rights reserved.
* Licensed under the MIT license. See LICENSE file in the project root for details.
* SPDX-License-Identifier: MIT
*/
/* splat - This example renders Gaussian splats as translucent ellipses.
*
* What to look for: positions place each splat, colors set the tint, sigma gives the two
* screen-space ellipse radii, and angles rotate the ellipses. Compare overlapping areas and the
* soft footprint shape to see how uncertain samples, local point spread, or projected density can
* be shown without drawing hard-edged markers.
*
* Scenario: visuals_splat
* Style: visuals, graphite_cyan, 1280x720 window target
*
* Build: just example-c visuals/splat
* Run: ./build/examples/c/visuals/splat --live
* Smoke: ./build/examples/c/visuals/splat --png
*/
/*************************************************************************************************/
/* Includes */
/*************************************************************************************************/
#include <math.h>
#include <stdbool.h>
#include <stdint.h>
#include "_assertions.h"
#include "datoviz/scene.h"
#include "example_style.h"
#include "runner/scenario_runner.h"
/*************************************************************************************************/
/* Constants */
/*************************************************************************************************/
#define WIDTH EXAMPLE_WINDOW_WIDTH
#define HEIGHT EXAMPLE_WINDOW_HEIGHT
#define SPLAT_COUNT 84u
static const float TAU = 6.28318530718f;
/*************************************************************************************************/
/* Helpers */
/*************************************************************************************************/
/**
* Fill a small deterministic Gaussian splat cloud.
*
* @param positions output splat centers
* @param colors output splat colors
* @param sigma output screen-space ellipse radii in pixels
* @param angles output ellipse angles in radians
*/
static void _fill_splats(
vec3 positions[SPLAT_COUNT], DvzColor colors[SPLAT_COUNT], vec2 sigma[SPLAT_COUNT],
float angles[SPLAT_COUNT])
{
ANN(positions);
ANN(colors);
ANN(sigma);
ANN(angles);
const ExampleStyleColorRole roles[] = {
EXAMPLE_STYLE_COLOR_ACCENT_PRIMARY,
EXAMPLE_STYLE_COLOR_ACCENT_SECONDARY,
EXAMPLE_STYLE_COLOR_WARNING,
EXAMPLE_STYLE_COLOR_ERROR,
};
for (uint32_t i = 0; i < SPLAT_COUNT; i++)
{
const float t = SPLAT_COUNT > 1u ? (float)i / (float)(SPLAT_COUNT - 1u) : 0.0f;
const float arm = (float)(i % 7u);
const float local = (float)(i / 7u) / (float)(SPLAT_COUNT / 7u);
const float theta = TAU * (1.55f * local + arm / 7.0f);
const float radius = 0.10f + 0.78f * sqrtf(local);
positions[i][0] = radius * cosf(theta);
positions[i][1] = 0.76f * radius * sinf(theta);
positions[i][2] = 0.01f * sinf(TAU * t);
colors[i] = example_graphite_cyan_color(roles[i % DVZ_ARRAY_COUNT(roles)]);
colors[i].a = 118u + (uint8_t)(64u * (i % 3u));
sigma[i][0] = 10.0f + 7.5f * (0.5f + 0.5f * sinf(TAU * (t + 0.11f * arm)));
sigma[i][1] = 4.0f + 4.5f * (0.5f + 0.5f * cosf(TAU * (0.7f * t + 0.05f * arm)));
angles[i] = theta + 0.45f * sinf(TAU * t);
}
}
/**
* Add one retained Gaussian splat visual to the panel.
*
* @param scene scene owning the visual
* @param panel panel receiving the visual
* @return true when the visual was added
*/
static bool _add_splats(DvzScene* scene, DvzPanel* panel)
{
ANN(scene);
ANN(panel);
vec3 positions[SPLAT_COUNT] = {{0}};
DvzColor colors[SPLAT_COUNT] = {{0}};
vec2 sigma[SPLAT_COUNT] = {{0}};
float angles[SPLAT_COUNT] = {0};
_fill_splats(positions, colors, sigma, angles);
DvzVisual* visual = dvz_splat(scene, 0);
if (visual == NULL)
return false;
DvzVisualDataUpdate updates[] = {
{.attr_name = "position", .data = positions, .item_count = SPLAT_COUNT},
{.attr_name = "color", .data = colors, .item_count = SPLAT_COUNT},
{.attr_name = "sigma", .data = sigma, .item_count = SPLAT_COUNT},
{.attr_name = "angle", .data = angles, .item_count = SPLAT_COUNT},
};
if (dvz_visual_set_data_many(visual, updates, 4) != 0)
return false;
return dvz_panel_add_visual(panel, visual, NULL) == 0;
}
/*************************************************************************************************/
/* Scenario callbacks */
/*************************************************************************************************/
/**
* Initialize the retained Gaussian splat visual scenario.
*
* @param ctx scenario context
* @param out_user scenario state output
* @return true on success
*/
static bool _scenario_init(DvzScenarioContext* ctx, void** out_user)
{
if (ctx == NULL)
return false;
if (out_user != NULL)
*out_user = NULL;
ctx->figure = dvz_figure(ctx->scene, ctx->width, ctx->height, 0);
if (ctx->figure == NULL)
return false;
DvzPanel* panel = dvz_panel_full(ctx->figure);
if (panel == NULL)
return false;
example_graphite_cyan_set_panel_background(panel);
if (!_add_splats(ctx->scene, panel))
return false;
DvzPanzoom* panzoom = dvz_scenario_panzoom(ctx, panel, NULL, DVZ_DIM_MASK_XY);
return panzoom != NULL;
}
/**
* Return the splat visual scenario specification.
*
* @return scenario specification
*/
static DvzScenarioSpec _splat_scenario(void)
{
return (DvzScenarioSpec){
.id = "visuals_splat",
.title = "Splat",
.width = WIDTH,
.height = HEIGHT,
.fps = 60.0,
.init = _scenario_init,
};
}
/*************************************************************************************************/
/* Functions */
/*************************************************************************************************/
/**
* Run the retained Gaussian splat visual example through the native scenario runner.
*
* @param argc command-line argument count
* @param argv command-line argument vector
* @return process exit code
*/
int main(int argc, char** argv)
{
DvzScenarioSpec spec = _splat_scenario();
return dvz_scenario_run_native_cli(&spec, argc, argv) == 0 ? 0 : 1;
}
Example details
- ID:
visuals_splat - Category:
visual - Lane:
visuals - Status:
experimental - Source:
examples/c/visuals/splat.c - Approved adaptation starter:
no - Reference: Splat visual family
- Browser support: Deferred
- Browser note: splat rendering is experimental and outside the RC browser subset
- Browser capability tags:
splat,alpha-blending,panzoom - Validation:
smoke+screenshot
Tags
splat, panzoom, capture
Data
| Field | Value |
|---|---|
kind |
synthetic |