/*******************************************************************************************
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*
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* raylib [shapes] example - rlgl triangle
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*
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* Example complexity rating: [★★☆☆] 2/4
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*
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* Example originally created with raylib 5.6-dev, last time updated with raylib 5.6-dev
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*
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* Example contributed by Robin (@RobinsAviary) and reviewed by Ramon Santamaria (@raysan5)
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*
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* Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
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* BSD-like license that allows static linking with closed source software
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*
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* Copyright (c) 2025-2025 Robin (@RobinsAviary)
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*
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********************************************************************************************/
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#include "raylib.h"
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#include "rlgl.h"
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//------------------------------------------------------------------------------------
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// Program main entry point
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//------------------------------------------------------------------------------------
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int main(void)
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{
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// Initialization
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//--------------------------------------------------------------------------------------
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const int screenWidth = 800;
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const int screenHeight = 450;
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SetConfigFlags(FLAG_MSAA_4X_HINT);
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InitWindow(screenWidth, screenHeight, "raylib [shapes] example - rlgl triangle");
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// Starting postions and rendered triangle positions
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Vector2 startingPositions[3] = {{ 400.0f, 150.0f }, { 300.0f, 300.0f }, { 500.0f, 300.0f }};
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Vector2 trianglePositions[3] = { startingPositions[0], startingPositions[1], startingPositions[2] };
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// Currently selected vertex, -1 means none
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int triangleIndex = -1;
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bool linesMode = false;
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float handleRadius = 8.0f;
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SetTargetFPS(60);
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//--------------------------------------------------------------------------------------
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// Main game loop
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while (!WindowShouldClose()) // Detect window close button or ESC key
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{
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// Update
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//----------------------------------------------------------------------------------
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if (IsKeyPressed(KEY_SPACE)) linesMode = !linesMode;
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// Check selected vertex
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for (unsigned int i = 0; i < 3; i++)
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{
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// If the mouse is within the handle circle
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if (CheckCollisionPointCircle(GetMousePosition(), trianglePositions[i], handleRadius) &&
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IsMouseButtonDown(MOUSE_BUTTON_LEFT))
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{
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triangleIndex = i;
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break;
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}
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}
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// If the user has selected a vertex, offset it by the mouse's delta this frame
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if (triangleIndex != -1)
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{
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Vector2 *position = &trianglePositions[triangleIndex];
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Vector2 mouseDelta = GetMouseDelta();
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position->x += mouseDelta.x;
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position->y += mouseDelta.y;
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}
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// Reset index on release
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if (IsMouseButtonReleased(MOUSE_BUTTON_LEFT)) triangleIndex = -1;
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// Enable/disable backface culling (2-sided triangles, slower to render)
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if (IsKeyPressed(KEY_LEFT)) rlEnableBackfaceCulling();
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if (IsKeyPressed(KEY_RIGHT)) rlDisableBackfaceCulling();
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// Reset triangle vertices to starting positions and reset backface culling
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if (IsKeyPressed(KEY_R))
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{
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trianglePositions[0] = startingPositions[0];
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trianglePositions[1] = startingPositions[1];
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trianglePositions[2] = startingPositions[2];
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rlEnableBackfaceCulling();
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}
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//----------------------------------------------------------------------------------
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// Draw
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//----------------------------------------------------------------------------------
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BeginDrawing();
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ClearBackground(RAYWHITE);
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if (linesMode)
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{
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// Draw triangle with lines
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rlBegin(RL_LINES);
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// Three lines, six points
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// Define color for next vertex
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rlColor4ub(255, 0, 0, 255);
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// Define vertex
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rlVertex2f(trianglePositions[0].x, trianglePositions[0].y);
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rlColor4ub(0, 255, 0, 255);
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rlVertex2f(trianglePositions[1].x, trianglePositions[1].y);
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rlColor4ub(0, 255, 0, 255);
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rlVertex2f(trianglePositions[1].x, trianglePositions[1].y);
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rlColor4ub(0, 0, 255, 255);
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rlVertex2f(trianglePositions[2].x, trianglePositions[2].y);
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rlColor4ub(0, 0, 255, 255);
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rlVertex2f(trianglePositions[2].x, trianglePositions[2].y);
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rlColor4ub(255, 0, 0, 255);
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rlVertex2f(trianglePositions[0].x, trianglePositions[0].y);
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rlEnd();
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}
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else
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{
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// Draw triangle as a triangle
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rlBegin(RL_TRIANGLES);
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// One triangle, three points
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// Define color for next vertex
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rlColor4ub(255, 0, 0, 255);
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// Define vertex
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rlVertex2f(trianglePositions[0].x, trianglePositions[0].y);
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rlColor4ub(0, 255, 0, 255);
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rlVertex2f(trianglePositions[1].x, trianglePositions[1].y);
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rlColor4ub(0, 0, 255, 255);
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rlVertex2f(trianglePositions[2].x, trianglePositions[2].y);
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rlEnd();
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}
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// Render the vertex handles, reacting to mouse movement/input
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for (unsigned int i = 0; i < 3; i++)
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{
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// Draw handle fill focused by mouse
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if (CheckCollisionPointCircle(GetMousePosition(), trianglePositions[i], handleRadius))
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DrawCircleV(trianglePositions[i], handleRadius, ColorAlpha(DARKGRAY, 0.5f));
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// Draw handle fill selected
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if (i == triangleIndex) DrawCircleV(trianglePositions[i], handleRadius, DARKGRAY);
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// Draw handle outline
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DrawCircleLinesV(trianglePositions[i], handleRadius, BLACK);
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}
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// Draw controls
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DrawText("SPACE: Toggle lines mode", 10, 10, 20, DARKGRAY);
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DrawText("LEFT-RIGHT: Toggle backface culling", 10, 40, 20, DARKGRAY);
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DrawText("MOUSE: Click and drag vertex points", 10, 70, 20, DARKGRAY);
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DrawText("R: Reset triangle to start positions", 10, 100, 20, DARKGRAY);
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EndDrawing();
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//----------------------------------------------------------------------------------
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}
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// De-Initialization
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//--------------------------------------------------------------------------------------
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CloseWindow(); // Close window and OpenGL context
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//--------------------------------------------------------------------------------------
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return 0;
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}
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