h-raylib-6.1.0.0: raylib/examples/models/models_mesh_uv_painting.c
/*******************************************************************************************
*
* raylib [models] example - mesh uv painting
*
* Example demonstrates painting directly onto a mesh's texture: a ray is cast from the
* mouse into the scene, the hit triangle is found, and the hit point is converted into
* UV space using barycentric interpolation so a brush stroke can be drawn on the texture
*
* Example complexity rating: [★★★★] 4/4
*
* Example originally created with raylib 6.0, last time updated with raylib 6.0
*
* Example contributed by PanicTitan (@PanicTitan) and reviewed by Ramon Santamaria (@raysan5)
*
* Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
* BSD-like license that allows static linking with closed source software
*
* Copyright (c) 2025 PanicTitan (@PanicTitan)
*
********************************************************************************************/
#include "raylib.h"
#include "raymath.h"
#define RAYGUI_IMPLEMENTATION
#include "raygui.h"
#include <math.h> // Required for: fabsf(), floorf()
#include <stddef.h> // Required for: NULL
//--------------------------------------------------------------------------------------
// Global Definitions
//--------------------------------------------------------------------------------------
#define CANVAS_SIZE 512
#define PALETTE_COUNT 8
//--------------------------------------------------------------------------------------
// Types and Structures Definition
//--------------------------------------------------------------------------------------
typedef enum { TOOL_PAINT = 0, TOOL_PICKER } ToolMode;
typedef enum { SHAPE_SPHERE = 0, SHAPE_CUBE, SHAPE_CYLINDER, SHAPE_TORUS } ShapeType;
//------------------------------------------------------------------------------------
// Module Functions Declaration
//------------------------------------------------------------------------------------
static void ChangeShape(Model *model, BoundingBox *bbox, ShapeType *currentShape, ShapeType newShape, Texture2D canvasTexture);
static bool GetMeshHitUV(Ray ray, Model model, BoundingBox bbox, Vector2 *outUV);
//------------------------------------------------------------------------------------
// Program main entry point
//------------------------------------------------------------------------------------
int main(void)
{
// Initialization
//--------------------------------------------------------------------------------------
const int screenWidth = 800;
const int screenHeight = 450;
InitWindow(screenWidth, screenHeight, "raylib [models] example - mesh uv painting");
Camera3D camera = { 0 };
camera.position = (Vector3){ 0.0f, 3.5f, 6.5f };
camera.target = (Vector3){ 0.0f, 0.0f, 0.0f };
camera.up = (Vector3){ 0.0f, 1.0f, 0.0f };
camera.fovy = 45.0f;
camera.projection = CAMERA_PERSPECTIVE;
// CPU-side canvas plus the GPU texture it gets pushed to after every stroke
Image canvasImage = GenImageColor(CANVAS_SIZE, CANVAS_SIZE, RAYWHITE);
Texture2D canvasTexture = LoadTextureFromImage(canvasImage);
SetTextureFilter(canvasTexture, TEXTURE_FILTER_BILINEAR);
Model model = { 0 };
BoundingBox modelBBox = { 0 };
ShapeType currentShape = SHAPE_SPHERE;
ChangeShape(&model, &modelBBox, ¤tShape, SHAPE_SPHERE, canvasTexture);
ToolMode currentTool = TOOL_PAINT;
Color activeColor = RED;
int brushRadius = 12;
Vector2 lastHitUV = { 0 };
bool hasLastHit = false;
Color palette[PALETTE_COUNT] = { RED, ORANGE, GOLD, LIME, SKYBLUE, PURPLE, DARKGRAY, WHITE };
Rectangle uiPanelRec = { 10.0f, 10.0f, 230.0f, 490.0f };
SetTargetFPS(60);
//--------------------------------------------------------------------------------------
// Main game loop
while (!WindowShouldClose()) // Detect window close button or ESC key
{
// Update
//----------------------------------------------------------------------------------
Vector2 mousePos = GetMousePosition();
bool isMouseOverUI = CheckCollisionPointRec(mousePos, uiPanelRec);
if (IsMouseButtonDown(MOUSE_BUTTON_RIGHT)) UpdateCamera(&camera, CAMERA_THIRD_PERSON);
if (!isMouseOverUI && IsMouseButtonDown(MOUSE_BUTTON_LEFT))
{
Ray ray = GetScreenToWorldRay(mousePos, camera);
Vector2 hitUV = { 0 };
if (GetMeshHitUV(ray, model, modelBBox, &hitUV))
{
int px = (int)(hitUV.x * CANVAS_SIZE);
int py = (int)(hitUV.y * CANVAS_SIZE);
if (currentTool == TOOL_PAINT)
{
// Stroke from the last hit to this one, guarding against jumps across a UV seam
if (hasLastHit && (fabsf(hitUV.x - lastHitUV.x) < 0.25f) && (fabsf(hitUV.y - lastHitUV.y) < 0.25f))
{
int lastPx = (int)(lastHitUV.x * CANVAS_SIZE);
int lastPy = (int)(lastHitUV.y * CANVAS_SIZE);
float dist = Vector2Distance((Vector2){ (float)lastPx, (float)lastPy }, (Vector2){ (float)px, (float)py });
int steps = (int)(dist / 2.0f) + 1;
for (int i = 0; i <= steps; i++)
{
float t = (float)i / (float)steps;
ImageDrawCircle(&canvasImage, (int)Lerp((float)lastPx, (float)px, t),
(int)Lerp((float)lastPy, (float)py, t), brushRadius, activeColor);
}
}
else ImageDrawCircle(&canvasImage, px, py, brushRadius, activeColor);
UpdateTexture(canvasTexture, canvasImage.data);
lastHitUV = hitUV;
hasLastHit = true;
}
else
{
activeColor = GetImageColor(canvasImage, px, py);
currentTool = TOOL_PAINT;
hasLastHit = false;
}
}
else hasLastHit = false;
}
else hasLastHit = false;
//----------------------------------------------------------------------------------
// Draw
//----------------------------------------------------------------------------------
BeginDrawing();
ClearBackground((Color){ 30, 32, 40, 255 });
BeginMode3D(camera);
DrawModel(model, Vector3Zero(), 1.0f, WHITE);
DrawGrid(10, 1.0f);
EndMode3D();
// Side panel
DrawRectangleRec(uiPanelRec, Fade(BLACK, 0.8f));
DrawRectangleLinesEx(uiPanelRec, 2.0f, DARKGRAY);
DrawText("MESH UV PAINTER", 25, 22, 20, GOLD);
// Tool selection toggles
bool paintActive = (currentTool == TOOL_PAINT);
bool pickerActive = (currentTool == TOOL_PICKER);
if (GuiToggle((Rectangle){ 25, 55, 95, 32 }, "PAINT", &paintActive)) currentTool = TOOL_PAINT;
if (GuiToggle((Rectangle){ 125, 55, 95, 32 }, "PICKER", &pickerActive)) currentTool = TOOL_PICKER;
// Shape selection toggles
DrawText("Mesh Shape:", 25, 100, 10, LIGHTGRAY);
bool sphereActive = (currentShape == SHAPE_SPHERE);
bool cubeActive = (currentShape == SHAPE_CUBE);
bool cylinderActive = (currentShape == SHAPE_CYLINDER);
bool torusActive = (currentShape == SHAPE_TORUS);
if (GuiToggle((Rectangle){ 25, 120, 95, 28 }, "SPHERE", &sphereActive))
ChangeShape(&model, &modelBBox, ¤tShape, SHAPE_SPHERE, canvasTexture);
if (GuiToggle((Rectangle){ 125, 120, 95, 28 }, "CUBE", &cubeActive))
ChangeShape(&model, &modelBBox, ¤tShape, SHAPE_CUBE, canvasTexture);
if (GuiToggle((Rectangle){ 25, 153, 95, 28 }, "CYLINDER", &cylinderActive))
ChangeShape(&model, &modelBBox, ¤tShape, SHAPE_CYLINDER, canvasTexture);
if (GuiToggle((Rectangle){ 125, 153, 95, 28 }, "TORUS", &torusActive))
ChangeShape(&model, &modelBBox, ¤tShape, SHAPE_TORUS, canvasTexture);
// Color display
DrawText("Active Color:", 25, 195, 10, LIGHTGRAY);
DrawRectangle(125, 193, 95, 20, activeColor);
DrawRectangleLines(125, 193, 95, 20, WHITE);
// Color swatches
DrawText("Palette Swatches:", 25, 225, 10, LIGHTGRAY);
for (int i = 0; i < PALETTE_COUNT; i++)
{
Rectangle swatchRec = { 25.0f + (i%4)*48, 245.0f + (i/4)*45, 40.0f, 38.0f };
DrawRectangleRec(swatchRec, palette[i]);
DrawRectangleLinesEx(swatchRec, 1.0f, WHITE);
if (CheckCollisionPointRec(mousePos, swatchRec) && IsMouseButtonPressed(MOUSE_BUTTON_LEFT)) activeColor = palette[i];
}
// Brush size buttons
DrawText(TextFormat("Brush Size: %dpx", brushRadius), 25, 345, 10, LIGHTGRAY);
if (GuiButton((Rectangle){ 25, 365, 95, 30 }, "SIZE -") && (brushRadius > 2)) brushRadius -= 2;
if (GuiButton((Rectangle){ 125, 365, 95, 30 }, "SIZE +") && (brushRadius < 64)) brushRadius += 2;
// Canvas action buttons
if (GuiButton((Rectangle){ 25, 410, 95, 30 }, "CLEAR"))
{
ImageClearBackground(&canvasImage, RAYWHITE);
UpdateTexture(canvasTexture, canvasImage.data);
}
if (GuiButton((Rectangle){ 125, 410, 95, 30 }, "FILL"))
{
ImageClearBackground(&canvasImage, activeColor);
UpdateTexture(canvasTexture, canvasImage.data);
}
DrawText("Left click: paint / pick color | Right drag: orbit camera", 260, screenHeight - 25, 10, RAYWHITE);
DrawFPS(screenWidth - 90, 15);
EndDrawing();
//----------------------------------------------------------------------------------
}
// De-Initialization
//--------------------------------------------------------------------------------------
UnloadModel(model);
UnloadImage(canvasImage);
UnloadTexture(canvasTexture);
CloseWindow(); // Close window and OpenGL context
//--------------------------------------------------------------------------------------
return 0;
}
//----------------------------------------------------------------------------------
// Module Functions Definition
//----------------------------------------------------------------------------------
// Unloads the current model and builds a new primitive shape in its place, sharing the
// same canvas texture, and recomputes the transformed bounding box used for ray testing
static void ChangeShape(Model *model, BoundingBox *bbox, ShapeType *currentShape, ShapeType newShape, Texture2D canvasTexture)
{
UnloadModel(*model);
Mesh mesh = { 0 };
switch (newShape)
{
case SHAPE_SPHERE: mesh = GenMeshSphere(1.5f, 32, 32); break;
case SHAPE_CUBE: mesh = GenMeshCube(2.2f, 2.2f, 2.2f); break;
case SHAPE_CYLINDER: mesh = GenMeshCylinder(1.2f, 2.5f, 24); break;
case SHAPE_TORUS: mesh = GenMeshTorus(0.6f, 1.6f, 24, 36); break;
default: mesh = GenMeshSphere(1.5f, 32, 32); break;
}
*model = LoadModelFromMesh(mesh);
// GenMeshCylinder builds upward from y = 0; shift it down to center on the origin
if (newShape == SHAPE_CYLINDER) model->transform = MatrixTranslate(0.0f, -1.25f, 0.0f);
model->materials[0].maps[MATERIAL_MAP_DIFFUSE].texture = canvasTexture;
BoundingBox box = GetMeshBoundingBox(model->meshes[0]);
box.min = Vector3Transform(box.min, model->transform);
box.max = Vector3Transform(box.max, model->transform);
*bbox = box;
*currentShape = newShape;
}
// Raycasts against the model's mesh triangles and returns the UV coordinate of the
// closest hit, interpolated from the hit triangle's vertices with barycentric weights
static bool GetMeshHitUV(Ray ray, Model model, BoundingBox bbox, Vector2 *outUV)
{
if (!GetRayCollisionBox(ray, bbox).hit) return false; // Fast reject
Mesh mesh = model.meshes[0];
float closestDistance = 1e9f;
bool found = false;
Vector2 hitUV = { 0 };
for (int tri = 0; tri < mesh.triangleCount; tri++)
{
int i0, i1, i2;
if (mesh.indices != NULL)
{
i0 = mesh.indices[3*tri + 0];
i1 = mesh.indices[3*tri + 1];
i2 = mesh.indices[3*tri + 2];
}
else { i0 = 3*tri; i1 = 3*tri + 1; i2 = 3*tri + 2; }
Vector3 a = Vector3Transform((Vector3){ mesh.vertices[3*i0], mesh.vertices[3*i0 + 1], mesh.vertices[3*i0 + 2] }, model.transform);
Vector3 b = Vector3Transform((Vector3){ mesh.vertices[3*i1], mesh.vertices[3*i1 + 1], mesh.vertices[3*i1 + 2] }, model.transform);
Vector3 c = Vector3Transform((Vector3){ mesh.vertices[3*i2], mesh.vertices[3*i2 + 1], mesh.vertices[3*i2 + 2] }, model.transform);
RayCollision hit = GetRayCollisionTriangle(ray, a, b, c);
if (hit.hit && (hit.distance < closestDistance))
{
closestDistance = hit.distance;
found = true;
Vector2 uvA = { mesh.texcoords[2*i0], mesh.texcoords[2*i0 + 1] };
Vector2 uvB = { mesh.texcoords[2*i1], mesh.texcoords[2*i1 + 1] };
Vector2 uvC = { mesh.texcoords[2*i2], mesh.texcoords[2*i2 + 1] };
Vector3 w = Vector3Barycenter(hit.point, a, b, c);
hitUV.x = w.x*uvA.x + w.y*uvB.x + w.z*uvC.x;
hitUV.y = w.x*uvA.y + w.y*uvB.y + w.z*uvC.y;
// Wrap into [0, 1] in case of minor floating point drift at UV seams
hitUV.x -= floorf(hitUV.x);
hitUV.y -= floorf(hitUV.y);
}
}
if (found && (outUV != NULL)) *outUV = hitUV;
return found;
}