rlgl triangle
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//! raylib [shapes] example - rlgl triangle
//!
//! Zig-API translation of examples/shapes/shapes_rlgl_triangle.c (raylib 6.2).
//! Example contributed by Robin (@RobinsAviary) and reviewed by Ramon Santamaria (@raysan5)
//! Example licensed under an unmodified zlib/libpng license.
//! Copyright (c) 2025 Robin (@RobinsAviary)
const rl = @import("raylib");
pub fn main() void {
// Initialization
const screen_width = 800;
const screen_height = 450;
rl.setConfigFlags(.{ .msaa_4x_hint = true });
rl.initWindow(screen_width, screen_height, "raylib [shapes] example - rlgl triangle");
defer rl.closeWindow(); // Close window and OpenGL context
// Starting postions and rendered triangle positions
const starting_positions = [3]rl.Vector2{ .{ .x = 400.0, .y = 150.0 }, .{ .x = 300.0, .y = 300.0 }, .{ .x = 500.0, .y = 300.0 } };
var triangle_positions = starting_positions;
// Currently selected vertex, null means none
var triangle_index: ?usize = null;
var lines_mode = false;
const handle_radius: f32 = 8.0;
rl.setTargetFPS(60);
// Main game loop
while (!rl.windowShouldClose()) { // Detect window close button or ESC key
// Update
if (rl.isKeyPressed(.space)) lines_mode = !lines_mode;
// Check selected vertex
for (triangle_positions, 0..) |position, i| {
// If the mouse is within the handle circle
if (rl.checkCollisionPointCircle(rl.getMousePosition(), position, handle_radius) and
rl.isMouseButtonDown(.left))
{
triangle_index = i;
break;
}
}
// If the user has selected a vertex, offset it by the mouse's delta this frame
if (triangle_index) |i| {
const position = &triangle_positions[i];
const mouse_delta = rl.getMouseDelta();
position.x += mouse_delta.x;
position.y += mouse_delta.y;
}
// Reset index on release
if (rl.isMouseButtonReleased(.left)) triangle_index = null;
// Enable/disable backface culling (2-sided triangles, slower to render)
if (rl.isKeyPressed(.left)) rl.gl.enableBackfaceCulling();
if (rl.isKeyPressed(.right)) rl.gl.disableBackfaceCulling();
// Reset triangle vertices to starting positions and reset backface culling
if (rl.isKeyPressed(.r)) {
triangle_positions = starting_positions;
rl.gl.enableBackfaceCulling();
}
// Draw
rl.beginDrawing();
defer rl.endDrawing();
rl.clearBackground(.ray_white);
const p = triangle_positions;
if (lines_mode) {
// Draw triangle with lines
rl.gl.begin(rl.gl.lines);
// Three lines, six points
// Define color for next vertex
rl.gl.color4ub(255, 0, 0, 255);
// Define vertex
rl.gl.vertex2f(p[0].x, p[0].y);
rl.gl.color4ub(0, 255, 0, 255);
rl.gl.vertex2f(p[1].x, p[1].y);
rl.gl.color4ub(0, 255, 0, 255);
rl.gl.vertex2f(p[1].x, p[1].y);
rl.gl.color4ub(0, 0, 255, 255);
rl.gl.vertex2f(p[2].x, p[2].y);
rl.gl.color4ub(0, 0, 255, 255);
rl.gl.vertex2f(p[2].x, p[2].y);
rl.gl.color4ub(255, 0, 0, 255);
rl.gl.vertex2f(p[0].x, p[0].y);
rl.gl.end();
} else {
// Draw triangle as a triangle
rl.gl.begin(rl.gl.triangles);
// One triangle, three points
// Define color for next vertex
rl.gl.color4ub(255, 0, 0, 255);
// Define vertex
rl.gl.vertex2f(p[0].x, p[0].y);
rl.gl.color4ub(0, 255, 0, 255);
rl.gl.vertex2f(p[1].x, p[1].y);
rl.gl.color4ub(0, 0, 255, 255);
rl.gl.vertex2f(p[2].x, p[2].y);
rl.gl.end();
}
// Render the vertex handles, reacting to mouse movement/input
for (triangle_positions, 0..) |position, i| {
// Draw handle fill focused by mouse
if (rl.checkCollisionPointCircle(rl.getMousePosition(), position, handle_radius))
rl.drawCircleV(position, handle_radius, rl.colorAlpha(.dark_gray, 0.5));
// Draw handle fill selected
if (triangle_index == i) rl.drawCircleV(position, handle_radius, .dark_gray);
// Draw handle outline
rl.drawCircleLinesV(position, handle_radius, .black);
}
// Draw controls
rl.drawText("SPACE: Toggle lines mode", 10, 10, 20, .dark_gray);
rl.drawText("LEFT-RIGHT: Toggle backface culling", 10, 40, 20, .dark_gray);
rl.drawText("MOUSE: Click and drag vertex points", 10, 70, 20, .dark_gray);
rl.drawText("R: Reset triangle to start positions", 10, 100, 20, .dark_gray);
}
}/*******************************************************************************************
*
* raylib [shapes] example - rlgl triangle
*
* Example complexity rating: [★★☆☆] 2/4
*
* Example originally created with raylib 6.0, last time updated with raylib 6.0
*
* Example contributed by Robin (@RobinsAviary) 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 Robin (@RobinsAviary)
*
********************************************************************************************/
#include "raylib.h"
#include "rlgl.h"
//------------------------------------------------------------------------------------
// Program main entry point
//------------------------------------------------------------------------------------
int main(void)
{
// Initialization
//--------------------------------------------------------------------------------------
const int screenWidth = 800;
const int screenHeight = 450;
SetConfigFlags(FLAG_MSAA_4X_HINT);
InitWindow(screenWidth, screenHeight, "raylib [shapes] example - rlgl triangle");
// Starting postions and rendered triangle positions
Vector2 startingPositions[3] = {{ 400.0f, 150.0f }, { 300.0f, 300.0f }, { 500.0f, 300.0f }};
Vector2 trianglePositions[3] = { startingPositions[0], startingPositions[1], startingPositions[2] };
// Currently selected vertex, -1 means none
int triangleIndex = -1;
bool linesMode = false;
float handleRadius = 8.0f;
SetTargetFPS(60);
//--------------------------------------------------------------------------------------
// Main game loop
while (!WindowShouldClose()) // Detect window close button or ESC key
{
// Update
//----------------------------------------------------------------------------------
if (IsKeyPressed(KEY_SPACE)) linesMode = !linesMode;
// Check selected vertex
for (unsigned int i = 0; i < 3; i++)
{
// If the mouse is within the handle circle
if (CheckCollisionPointCircle(GetMousePosition(), trianglePositions[i], handleRadius) &&
IsMouseButtonDown(MOUSE_BUTTON_LEFT))
{
triangleIndex = i;
break;
}
}
// If the user has selected a vertex, offset it by the mouse's delta this frame
if (triangleIndex != -1)
{
Vector2 *position = &trianglePositions[triangleIndex];
Vector2 mouseDelta = GetMouseDelta();
position->x += mouseDelta.x;
position->y += mouseDelta.y;
}
// Reset index on release
if (IsMouseButtonReleased(MOUSE_BUTTON_LEFT)) triangleIndex = -1;
// Enable/disable backface culling (2-sided triangles, slower to render)
if (IsKeyPressed(KEY_LEFT)) rlEnableBackfaceCulling();
if (IsKeyPressed(KEY_RIGHT)) rlDisableBackfaceCulling();
// Reset triangle vertices to starting positions and reset backface culling
if (IsKeyPressed(KEY_R))
{
trianglePositions[0] = startingPositions[0];
trianglePositions[1] = startingPositions[1];
trianglePositions[2] = startingPositions[2];
rlEnableBackfaceCulling();
}
//----------------------------------------------------------------------------------
// Draw
//----------------------------------------------------------------------------------
BeginDrawing();
ClearBackground(RAYWHITE);
if (linesMode)
{
// Draw triangle with lines
rlBegin(RL_LINES);
// Three lines, six points
// Define color for next vertex
rlColor4ub(255, 0, 0, 255);
// Define vertex
rlVertex2f(trianglePositions[0].x, trianglePositions[0].y);
rlColor4ub(0, 255, 0, 255);
rlVertex2f(trianglePositions[1].x, trianglePositions[1].y);
rlColor4ub(0, 255, 0, 255);
rlVertex2f(trianglePositions[1].x, trianglePositions[1].y);
rlColor4ub(0, 0, 255, 255);
rlVertex2f(trianglePositions[2].x, trianglePositions[2].y);
rlColor4ub(0, 0, 255, 255);
rlVertex2f(trianglePositions[2].x, trianglePositions[2].y);
rlColor4ub(255, 0, 0, 255);
rlVertex2f(trianglePositions[0].x, trianglePositions[0].y);
rlEnd();
}
else
{
// Draw triangle as a triangle
rlBegin(RL_TRIANGLES);
// One triangle, three points
// Define color for next vertex
rlColor4ub(255, 0, 0, 255);
// Define vertex
rlVertex2f(trianglePositions[0].x, trianglePositions[0].y);
rlColor4ub(0, 255, 0, 255);
rlVertex2f(trianglePositions[1].x, trianglePositions[1].y);
rlColor4ub(0, 0, 255, 255);
rlVertex2f(trianglePositions[2].x, trianglePositions[2].y);
rlEnd();
}
// Render the vertex handles, reacting to mouse movement/input
for (unsigned int i = 0; i < 3; i++)
{
// Draw handle fill focused by mouse
if (CheckCollisionPointCircle(GetMousePosition(), trianglePositions[i], handleRadius))
DrawCircleV(trianglePositions[i], handleRadius, ColorAlpha(DARKGRAY, 0.5f));
// Draw handle fill selected
if (i == triangleIndex) DrawCircleV(trianglePositions[i], handleRadius, DARKGRAY);
// Draw handle outline
DrawCircleLinesV(trianglePositions[i], handleRadius, BLACK);
}
// Draw controls
DrawText("SPACE: Toggle lines mode", 10, 10, 20, DARKGRAY);
DrawText("LEFT-RIGHT: Toggle backface culling", 10, 40, 20, DARKGRAY);
DrawText("MOUSE: Click and drag vertex points", 10, 70, 20, DARKGRAY);
DrawText("R: Reset triangle to start positions", 10, 100, 20, DARKGRAY);
EndDrawing();
//----------------------------------------------------------------------------------
}
// De-Initialization
//--------------------------------------------------------------------------------------
CloseWindow(); // Close window and OpenGL context
//--------------------------------------------------------------------------------------
return 0;
}From raylib 6.2. The original on GitHub.