h-raylib-5.6.0.0: raylib/examples/textures/textures_framebuffer_rendering.c
/*******************************************************************************************
*
* raylib [textures] example - framebuffer rendering
*
* Example complexity rating: [★★☆☆] 2/4
*
* Example originally created with raylib 5.6, last time updated with raylib 5.6
*
* Example contributed by Jack Boakes (@jackboakes) 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) 2026 Jack Boakes (@jackboakes)
*
********************************************************************************************/
#include "raylib.h"
#include "raymath.h"
//------------------------------------------------------------------------------------
// Module Functions Declaration
//------------------------------------------------------------------------------------
static void DrawCameraPrism(Camera3D camera, float aspect, Color color);
//------------------------------------------------------------------------------------
// Program main entry point
//------------------------------------------------------------------------------------
int main(void)
{
// Initialization
//--------------------------------------------------------------------------------------
const int screenWidth = 800;
const int screenHeight = 450;
const int splitWidth = screenWidth/2;
InitWindow(screenWidth, screenHeight, "raylib [textures] example - framebuffer rendering");
// Camera to look at the 3D world
Camera3D subjectCamera = { 0 };
subjectCamera.position = (Vector3){ 5.0f, 5.0f, 5.0f };
subjectCamera.target = (Vector3){ 0.0f, 0.0f, 0.0f };
subjectCamera.up = (Vector3){ 0.0f, 1.0f, 0.0f };
subjectCamera.fovy = 45.0f;
subjectCamera.projection = CAMERA_PERSPECTIVE;
// Camera to observe the subject camera and 3D world
Camera3D observerCamera = { 0 };
observerCamera.position = (Vector3){ 10.0f, 10.0f, 10.0f };
observerCamera.target = (Vector3){ 0.0f, 0.0f, 0.0f };
observerCamera.up = (Vector3){ 0.0f, 1.0f, 0.0f };
observerCamera.fovy = 45.0f;
observerCamera.projection = CAMERA_PERSPECTIVE;
// Set up render textures
RenderTexture2D observerTarget = LoadRenderTexture(splitWidth, screenHeight);
Rectangle observerSource = { 0.0f, 0.0f, (float)observerTarget.texture.width, -(float)observerTarget.texture.height };
Rectangle observerDest = { 0.0f, 0.0f, (float)splitWidth, (float)screenHeight };
RenderTexture2D subjectTarget = LoadRenderTexture(splitWidth, screenHeight);
Rectangle subjectSource = { 0.0f, 0.0f, (float)subjectTarget.texture.width, -(float)subjectTarget.texture.height };
Rectangle subjectDest = { (float)splitWidth, 0.0f, (float)splitWidth, (float)screenHeight };
const float textureAspectRatio = (float)subjectTarget.texture.width/(float)subjectTarget.texture.height;
// Rectangles for cropping render texture
const float captureSize = 128.0f;
Rectangle cropSource = { (subjectTarget.texture.width - captureSize)/2.0f, (subjectTarget.texture.height - captureSize)/2.0f, captureSize, -captureSize };
Rectangle cropDest = { splitWidth + 20, 20, captureSize, captureSize};
SetTargetFPS(60);
DisableCursor();
//--------------------------------------------------------------------------------------
// Main game loop
while (!WindowShouldClose()) // Detect window close button or ESC key
{
// Update
//----------------------------------------------------------------------------------
UpdateCamera(&observerCamera, CAMERA_FREE);
UpdateCamera(&subjectCamera, CAMERA_ORBITAL);
if (IsKeyPressed(KEY_R)) observerCamera.target = (Vector3){ 0.0f, 0.0f, 0.0f };
// Build LHS observer view texture
BeginTextureMode(observerTarget);
ClearBackground(RAYWHITE);
BeginMode3D(observerCamera);
DrawGrid(10, 1.0f);
DrawCube((Vector3){ 0.0f, 0.0f, 0.0f }, 2.0f, 2.0f, 2.0f, GOLD);
DrawCubeWires((Vector3){ 0.0f, 0.0f, 0.0f }, 2.0f, 2.0f, 2.0f, PINK);
DrawCameraPrism(subjectCamera, textureAspectRatio, GREEN);
EndMode3D();
DrawText("Observer View", 10, observerTarget.texture.height - 30, 20, BLACK);
DrawText("WASD + Mouse to Move", 10, 10, 20, DARKGRAY);
DrawText("Scroll to Zoom", 10, 30, 20, DARKGRAY);
DrawText("R to Reset Observer Target", 10, 50, 20, DARKGRAY);
EndTextureMode();
// Build RHS subject view texture
BeginTextureMode(subjectTarget);
ClearBackground(RAYWHITE);
BeginMode3D(subjectCamera);
DrawCube((Vector3){ 0.0f, 0.0f, 0.0f }, 2.0f, 2.0f, 2.0f, GOLD);
DrawCubeWires((Vector3){ 0.0f, 0.0f, 0.0f }, 2.0f, 2.0f, 2.0f, PINK);
DrawGrid(10, 1.0f);
EndMode3D();
DrawRectangleLines((subjectTarget.texture.width - captureSize)/2, (subjectTarget.texture.height - captureSize)/2, captureSize, captureSize, GREEN);
DrawText("Subject View", 10, subjectTarget.texture.height - 30, 20, BLACK);
EndTextureMode();
//----------------------------------------------------------------------------------
// Draw
//----------------------------------------------------------------------------------
BeginDrawing();
ClearBackground(BLACK);
// Draw observer texture LHS
DrawTexturePro(observerTarget.texture, observerSource, observerDest, (Vector2){0.0f, 0.0f }, 0.0f, WHITE);
// Draw subject texture RHS
DrawTexturePro(subjectTarget.texture, subjectSource, subjectDest, (Vector2){ 0.0f, 0.0f }, 0.0f, WHITE);
// Draw the small crop overlay on top
DrawTexturePro(subjectTarget.texture, cropSource, cropDest, (Vector2){ 0.0f, 0.0f }, 0.0f, WHITE);
DrawRectangleLinesEx(cropDest, 2, BLACK);
// Draw split screen divider line
DrawLine(splitWidth, 0, splitWidth, screenHeight, BLACK);
EndDrawing();
//----------------------------------------------------------------------------------
}
// De-Initialization
//--------------------------------------------------------------------------------------
UnloadRenderTexture(observerTarget);
UnloadRenderTexture(subjectTarget);
CloseWindow(); // Close window and OpenGL context
//--------------------------------------------------------------------------------------
return 0;
}
//----------------------------------------------------------------------------------
// Module Functions Definition
//----------------------------------------------------------------------------------
static void DrawCameraPrism(Camera3D camera, float aspect, Color color)
{
float length = Vector3Distance(camera.position, camera.target);
// Define the 4 corners of the camera's prism plane sliced at the target in Normalized Device Coordinates
Vector3 planeNDC[4] = {
{ -1.0f, -1.0f, 1.0f }, // Bottom Left
{ 1.0f, -1.0f, 1.0f }, // Bottom Right
{ 1.0f, 1.0f, 1.0f }, // Top Right
{ -1.0f, 1.0f, 1.0f } // Top Left
};
// Build the matrices
Matrix view = GetCameraMatrix(camera);
Matrix proj = MatrixPerspective(camera.fovy * DEG2RAD, aspect, 0.05f, length);
// Combine view and projection so we can reverse the full camera transform
Matrix viewProj = MatrixMultiply(view, proj);
// Invert the view-projection matrix to unproject points from NDC space back into world space
Matrix inverseViewProj = MatrixInvert(viewProj);
// Transform the 4 plane corners from NDC into world space
Vector3 corners[4];
for (int i = 0; i < 4; i++)
{
float x = planeNDC[i].x;
float y = planeNDC[i].y;
float z = planeNDC[i].z;
// Multiply NDC position by the inverse view-projection matrix
// This produces a homogeneous (x, y, z, w) position in world space
float vx = inverseViewProj.m0*x + inverseViewProj.m4*y + inverseViewProj.m8*z + inverseViewProj.m12;
float vy = inverseViewProj.m1*x + inverseViewProj.m5*y + inverseViewProj.m9*z + inverseViewProj.m13;
float vz = inverseViewProj.m2*x + inverseViewProj.m6*y + inverseViewProj.m10*z + inverseViewProj.m14;
float vw = inverseViewProj.m3*x + inverseViewProj.m7*y + inverseViewProj.m11*z + inverseViewProj.m15;
corners[i] = (Vector3){ vx/vw, vy/vw, vz/vw };
}
// Draw the far plane sliced at the target
DrawLine3D(corners[0], corners[1], color);
DrawLine3D(corners[1], corners[2], color);
DrawLine3D(corners[2], corners[3], color);
DrawLine3D(corners[3], corners[0], color);
// Draw the prism lines from the far plane to the camera position
for (int i = 0; i < 4; i++)
{
DrawLine3D(camera.position, corners[i], color);
}
}