/******************************************************************************************* * * raylib [other] example - 3d stencil buffer portal masking * * Example demonstrates 3D stencil buffer portal masking. * * Example complexity rating: [★★★☆] 3/4 * * 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 "rlgl.h" #include // Standard OpenGL defines for Stencil Buffer and Face Culling #ifndef GL_STENCIL_TEST #define GL_STENCIL_TEST 0x0B90 #define GL_STENCIL_BUFFER_BIT 0x00000400 #define GL_DEPTH_BUFFER_BIT 0x00000100 #define GL_CULL_FACE 0x0B44 #define GL_BACK 0x0405 #define GL_ALWAYS 0x0207 #define GL_EQUAL 0x0202 #define GL_REPLACE 0x1E01 #define GL_KEEP 0x1E00 #define GL_FALSE 0 #define GL_TRUE 1 #endif // External OpenGL function declarations #if defined(__cplusplus) extern "C" { #endif RLAPI void glEnable(unsigned int cap); RLAPI void glDisable(unsigned int cap); RLAPI void glClear(unsigned int mask); RLAPI void glStencilFunc(unsigned int func, int ref, unsigned int mask); RLAPI void glStencilOp(unsigned int sfail, unsigned int dpfail, unsigned int dppass); RLAPI void glColorMask(unsigned char red, unsigned char green, unsigned char blue, unsigned char alpha); RLAPI void glDepthMask(unsigned char flag); RLAPI void glCullFace(unsigned int mode); #if defined(__cplusplus) } #endif //------------------------------------------------------------------------------------ // Module Functions Declaration //------------------------------------------------------------------------------------ static void DrawPortalMaskPlane(float width, float height); //------------------------------------------------------------------------------------ // Program main entry point //------------------------------------------------------------------------------------ int main(void) { // Initialization //-------------------------------------------------------------------------------------- const int screenWidth = 1280; const int screenHeight = 720; InitWindow(screenWidth, screenHeight, "raylib [rlgl] example - 3d stencil buffer portal"); // Camera to navigate the 3D world Camera3D camera = { 0 }; camera.position = (Vector3){ 0.0f, 2.5f, 7.0f }; camera.target = (Vector3){ 0.0f, 1.8f, 0.0f }; camera.up = (Vector3){ 0.0f, 1.0f, 0.0f }; camera.fovy = 45.0f; camera.projection = CAMERA_PERSPECTIVE; DisableCursor(); // Lock cursor for first-person free camera controls SetTargetFPS(60); // Set target frame-rate //-------------------------------------------------------------------------------------- // Main game loop while (!WindowShouldClose()) // Detect window close button or ESC key { // Update //---------------------------------------------------------------------------------- UpdateCamera(&camera, CAMERA_FREE); float time = (float)GetTime(); //---------------------------------------------------------------------------------- // Draw //---------------------------------------------------------------------------------- BeginDrawing(); ClearBackground((Color){ 15, 18, 26, 255 }); // 1. Render Real World (Outside Portal) //------------------------------------------------------------------------------ BeginMode3D(camera); DrawGrid(20, 1.0f); // Real world side pillars DrawCube((Vector3){ -3.5f, 2.0f, 0.0f }, 0.8f, 4.0f, 0.8f, DARKGRAY); DrawCubeWires((Vector3){ -3.5f, 2.0f, 0.0f }, 0.8f, 4.0f, 0.8f, ORANGE); DrawCube((Vector3){ 3.5f, 2.0f, 0.0f }, 0.8f, 4.0f, 0.8f, DARKGRAY); DrawCubeWires((Vector3){ 3.5f, 2.0f, 0.0f }, 0.8f, 4.0f, 0.8f, ORANGE); // Golden archway front frame DrawCubeWires((Vector3){ 0.0f, 2.0f, 0.0f }, 3.2f, 4.2f, 0.2f, GOLD); DrawCube((Vector3){ 0.0f, 0.05f, 0.0f }, 3.4f, 0.1f, 0.6f, MAROON); // Solid back wall for the portal (visible when viewing from behind) DrawCube((Vector3){ 0.0f, 2.0f, -0.05f }, 3.1f, 4.1f, 0.05f, DARKBLUE); EndMode3D(); // Flush pending render batch before modifying OpenGL stencil state rlDrawRenderBatchActive(); // 2. Stencil Mask Pass (Write Portal Doorway to Stencil Buffer) //------------------------------------------------------------------------------ glEnable(GL_STENCIL_TEST); glClear(GL_STENCIL_BUFFER_BIT); // Reset stencil mask buffer to 0 // Enable backface culling so the back of the portal plane does not register glEnable(GL_CULL_FACE); glCullFace(GL_BACK); // Stencil settings: write '1' everywhere mask geometry is drawn glStencilFunc(GL_ALWAYS, 1, 0xFF); glStencilOp(GL_REPLACE, GL_REPLACE, GL_REPLACE); // Disable color and depth writes (mask geometry remains invisible) glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE); glDepthMask(GL_FALSE); BeginMode3D(camera); // Draw single-sided 2D quad mask plane facing +Z DrawPortalMaskPlane(3.0f, 4.0f); EndMode3D(); rlDrawRenderBatchActive(); // Restore culling state glDisable(GL_CULL_FACE); // 3. Render Secret World (Only where Stencil == 1) //------------------------------------------------------------------------------ // Restore color and depth writing glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE); glDepthMask(GL_TRUE); // Only render fragments where stencil buffer is equal to 1 glStencilFunc(GL_EQUAL, 1, 0xFF); glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP); // Clear depth buffer in stencil region so inner geometry renders properly glClear(GL_DEPTH_BUFFER_BIT); BeginMode3D(camera); // Secret world neon grid floor DrawGrid(30, 0.8f); // Floating pulsing core sphere inside alternate dimension Vector3 corePos = { 0.0f, 2.0f + sinf(time * 2.5f) * 0.4f, -4.0f }; DrawSphere(corePos, 1.2f, PURPLE); DrawSphereWires(corePos, 1.25f, 16, 16, MAGENTA); // Orbiting green cubes in alternate dimension for (int i = 0; i < 4; i++) { float angle = time * 1.5f + i * (PI / 2.0f); Vector3 pos = { sinf(angle) * 2.5f, 2.0f + cosf(time * 3.0f + i) * 0.5f, -4.0f + cosf(angle) * 2.5f }; DrawCube(pos, 0.5f, 0.5f, 0.5f, LIME); DrawCubeWires(pos, 0.52f, 0.52f, 0.52f, DARKGREEN); } EndMode3D(); rlDrawRenderBatchActive(); // 4. Cleanup & 2D HUD Overlay //------------------------------------------------------------------------------ glDisable(GL_STENCIL_TEST); // Overlay HUD DrawRectangle(15, 15, 420, 85, Fade(BLACK, 0.75f)); DrawRectangleLines(15, 15, 420, 85, GOLD); DrawText("3D STENCIL PORTAL DEMO", 28, 25, 20, GOLD); DrawText("Look through the golden arch into Dimension B", 28, 52, 14, RAYWHITE); DrawText("Controls: Mouse to look | WASD / Keys to move", 28, 72, 12, GRAY); EndDrawing(); //---------------------------------------------------------------------------------- } // De-Initialization //-------------------------------------------------------------------------------------- CloseWindow(); // Close window and OpenGL context //-------------------------------------------------------------------------------------- return 0; } //---------------------------------------------------------------------------------- // Module Functions Definition //---------------------------------------------------------------------------------- // Draw a single 1-sided 2D quad plane facing +Z used for stencil masking static void DrawPortalMaskPlane(float width, float height) { float hw = width / 2.0f; rlBegin(RL_QUADS); rlNormal3f(0.0f, 0.0f, 1.0f); // Counter-Clockwise (CCW) vertex order = Front Face rlVertex3f(-hw, 0.0f, 0.0f); rlVertex3f( hw, 0.0f, 0.0f); rlVertex3f( hw, height, 0.0f); rlVertex3f(-hw, height, 0.0f); rlEnd(); }