voxelThing/source/playerController.c

// playerController.c
#include "raylib.h"
#include "raymath.h"
#include "playerController.h"
#include "blockTypes.h"
#include <math.h>

void UpdatePlayer(Player *player) {
    Vector2 mouseDelta = GetMouseDelta();
    player->playerOrientation.x += mouseDelta.x * -0.002f;
    player->playerOrientation.y += mouseDelta.y * -0.002f;

    float limit = PI / 1.8f;
    if (player->playerOrientation.y > limit) player->playerOrientation.y = limit;
    if (player->playerOrientation.y < -limit) player->playerOrientation.y = -limit;

    float yaw = player->playerOrientation.x;
    float pitch = player->playerOrientation.y;

    player->forward = (Vector3){
        cosf(pitch) * sinf(yaw),
        sinf(pitch),
        cosf(pitch) * cosf(yaw)
    };

    player->right = (Vector3){
        sinf(yaw - PI/2.0f),
        0.0f,
        cosf(yaw - PI/2.0f)
    };

    Vector3 movement = {0};
    if (IsKeyDown(KEY_W)) movement = Vector3Add(movement, player->forward);
    if (IsKeyDown(KEY_S)) movement = Vector3Subtract(movement, player->forward);
    if (IsKeyDown(KEY_A)) movement = Vector3Subtract(movement, player->right);
    if (IsKeyDown(KEY_D)) movement = Vector3Add(movement, player->right);
    if (IsKeyDown(KEY_SPACE)) movement.y += 1.0f;
    if (IsKeyDown(KEY_LEFT_SHIFT)) movement.y -= 1.0f;

    if (Vector3Length(movement) > 0.0f)
        movement = Vector3Scale(Vector3Normalize(movement), player->moveSpeed * GetFrameTime());

    player->mapPosition = Vector3Add(player->mapPosition, movement);
    player->camera.position = player->mapPosition;
    player->camera.target = Vector3Add(player->mapPosition, player->forward);
}

// An implementation of DDA (digital differential analyzer), steps through each voxel boundary along a ray cast from origin along direction to maxDistance
RaycastHit RaycastChunk(const Chunk *chunk, Vector3 origin, Vector3 direction, float maxDistance) {
    RaycastHit result = {0}; // Initialize result: no hit, zeroed values

    direction = Vector3Normalize(direction); // Ensure direction is a unit vector

    // Nudge the origin slightly to avoid precision issues at block boundaries
    origin = Vector3Add(origin, Vector3Scale(direction, 0.001f));

    // Determine the next voxel boundary to cross along each axis
    float nextX = (direction.x >= 0) ? ceilf(origin.x) : floorf(origin.x);
    float nextY = (direction.y >= 0) ? ceilf(origin.y) : floorf(origin.y);
    float nextZ = (direction.z >= 0) ? ceilf(origin.z) : floorf(origin.z);

    // Get integer voxel coordinates for current position
    int x = (int)floorf(origin.x);
    int y = (int)floorf(origin.y);
    int z = (int)floorf(origin.z);

    // Determine step direction: +1 or -1 along each axis
    int stepX = (direction.x >= 0) ? 1 : -1;
    int stepY = (direction.y >= 0) ? 1 : -1;
    int stepZ = (direction.z >= 0) ? 1 : -1;

    // How far to travel along the ray to cross a voxel in each axis
    float tDeltaX = (direction.x == 0) ? INFINITY : fabsf(1.0f / direction.x);
    float tDeltaY = (direction.y == 0) ? INFINITY : fabsf(1.0f / direction.y);
    float tDeltaZ = (direction.z == 0) ? INFINITY : fabsf(1.0f / direction.z);

    // Distance from origin to the first voxel boundary (for each axis)
    float tMaxX = (direction.x == 0) ? INFINITY : (nextX - origin.x) / direction.x;
    float tMaxY = (direction.y == 0) ? INFINITY : (nextY - origin.y) / direction.y;
    float tMaxZ = (direction.z == 0) ? INFINITY : (nextZ - origin.z) / direction.z;

    float t = 0.0f; // Total traveled distance along the ray
    Vector3 lastNormal = {0}; // Which face was entered (used for highlighting/interactions)

    // Walk the ray through the voxel grid until we exceed maxDistance
    while (t < maxDistance) {
        // Check if the current voxel is inside the chunk bounds
        if (x >= 0 && y >= 0 && z >= 0 &&
            x < CHUNK_SIZE_X && y < CHUNK_SIZE_Y && z < CHUNK_SIZE_Z) {

            int blockID = chunk->blocks[x][y][z].type;

        // If it's not air, we hit something!
        if (blockID != BLOCK_AIR) {
            result.hit = true;
            result.blockID = blockID;
            result.position = (Vector3){x, y, z};
            result.normal = lastNormal;
            result.t = t;
            return result;
        }
            }

            // Move to the next voxel along the smallest tMax (i.e., the closest boundary)
            if (tMaxX < tMaxY && tMaxX < tMaxZ) {
                x += stepX;
                t = tMaxX;
                tMaxX += tDeltaX;
                lastNormal = (Vector3){-stepX, 0, 0}; // Normal points opposite the ray step
            } else if (tMaxY < tMaxZ) {
                y += stepY;
                t = tMaxY;
                tMaxY += tDeltaY;
                lastNormal = (Vector3){0, -stepY, 0};
            } else {
                z += stepZ;
                t = tMaxZ;
                tMaxZ += tDeltaZ;
                lastNormal = (Vector3){0, 0, -stepZ};
            }
    }

    // If no block was hit, return default (no hit)
    return result;
}


RaycastHit GetPlayerRaycastHit(Player *player, Chunk *chunk, float maxDistance) {
    Ray ray = {
        .position = player->mapPosition,
        .direction = Vector3Normalize(player->forward)
    };
    return RaycastChunk(chunk, ray.position, ray.direction, maxDistance);
}

void HandleBlockInteraction(Player *player, Chunk *chunk, RaycastHit hit, int blockSelection) {
    if (hit.hit && IsMouseButtonPressed(MOUSE_LEFT_BUTTON)) {
        chunk->blocks[(int)hit.position.x][(int)hit.position.y][(int)hit.position.z].type = BLOCK_AIR;
    }

    if (hit.hit && IsMouseButtonPressed(MOUSE_RIGHT_BUTTON)) {
        int px = (int)(hit.position.x + hit.normal.x);
        int py = (int)(hit.position.y + hit.normal.y);
        int pz = (int)(hit.position.z + hit.normal.z);

        if (px >= 0 && px < CHUNK_SIZE_X &&
            py >= 0 && py < CHUNK_SIZE_Y &&
            pz >= 0 && pz < CHUNK_SIZE_Z) {
            chunk->blocks[px][py][pz].type = blockSelection;
            }
    }
}