问题描述 #

开发平台游戏时遇到角色无法完全贴近墙体的问题，原因是碰撞检测触发后直接将dx从角色位置中减去，导致角色与墙体之间产生间隙。以下是当前的MovePlayer函数代码：

void MovePlayer()
{
    float dx = 0; 
    
    if(keys.right) dx += (plr.speed * g_deltaTime);
    if(keys.left) dx -= (plr.speed * g_deltaTime);


    plr.myCollider->position.x += dx;

    Collider *temp = collider_head.next;
    while(temp != NULL) {
        Collider *next = temp->next;
        if(temp != plr.myCollider && temp->type == COLLIDER_STATIC && isColliding(plr.myCollider, temp)) {
            plr.myCollider->position.x -= dx;


        }
        temp = next;
    }

    plr.y_velocity += GRAVITY * g_deltaTime;

    float dy = plr.y_velocity * g_deltaTime;
    plr.myCollider->position.y += dy;
    

    temp = collider_head.next;
    while(temp != NULL) {
        Collider *next = temp->next;
        if(temp != plr.myCollider && temp->type == COLLIDER_STATIC && isColliding(plr.myCollider, temp)) {
            plr.myCollider->position.y -= dy;
            if(plr.y_velocity > 0) {
                plr.grounded = TRUE;
            }

            plr.y_velocity = 0;
        }
        temp = next;
    }
    if(keys.up && plr.grounded) {
        plr.y_velocity = -110;
        plr.grounded = FALSE;
    }

    if(keys.up && plr.y_velocity < 0) {
        plr.y_velocity += -90.0f * g_deltaTime;
    }
}

修复思路 #

当前代码在碰撞后直接将角色位置回退整个dx（或dy），这会让角色回到移动前的位置，自然产生间隙。正确的做法是计算角色与墙体的重叠距离，只回退刚好消除重叠的距离，让角色刚好贴紧墙体。

具体修改步骤 #

1. 新增计算碰撞重叠量的函数，用于获取x、y轴的重叠数值：

typedef struct {
    float x;
    float y;
} CollisionOverlap;

CollisionOverlap CalculateCollisionOverlap(Collider* a, Collider* b) {
    CollisionOverlap overlap = {0};
    
    // 计算x轴重叠
    float aRight = a->position.x + a->width;
    float bRight = b->position.x + b->width;
    float aLeft = a->position.x;
    float bLeft = b->position.x;
    
    overlap.x = fmin(aRight, bRight) - fmax(aLeft, bLeft);
    
    // 计算y轴重叠
    float aBottom = a->position.y + a->height;
    float bBottom = b->position.y + b->height;
    float aTop = a->position.y;
    float bTop = b->position.y;
    
    overlap.y = fmin(aBottom, bBottom) - fmax(aTop, bTop);
    
    return overlap;
}

2. 修改x轴碰撞处理逻辑，替换原有的直接回退dx的代码：

// 原x轴碰撞判断块替换为：
if(temp != plr.myCollider && temp->type == COLLIDER_STATIC && isColliding(plr.myCollider, temp)) {
    CollisionOverlap overlap = CalculateCollisionOverlap(plr.myCollider, temp);
    // 根据移动方向调整位置，只消除重叠部分
    if(dx > 0) {
        // 向右移动撞墙，左移重叠量
        plr.myCollider->position.x -= overlap.x;
    } else if(dx < 0) {
        // 向左移动撞墙，右移重叠量
        plr.myCollider->position.x += overlap.x;
    }
}

3. 优化y轴碰撞处理，同样用重叠量替代回退整个dy：

// 原y轴碰撞判断块替换为：
if(temp != plr.myCollider && temp->type == COLLIDER_STATIC && isColliding(plr.myCollider, temp)) {
    CollisionOverlap overlap = CalculateCollisionOverlap(plr.myCollider, temp);
    if(dy > 0) {
        // 下落撞地面，上移重叠量
        plr.myCollider->position.y -= overlap.y;
        plr.grounded = TRUE;
    } else if(dy < 0) {
        // 跳跃撞天花板，下移重叠量
        plr.myCollider->position.y += overlap.y;
    }
    plr.y_velocity = 0;
}

关键说明 #

• 核心逻辑是只回退碰撞产生的重叠距离，而非整个移动量，这样角色会刚好贴合墙体/地面，不会出现间隙。
• 必须根据移动方向判断重叠量的调整方向，确保角色向正确的方向移动以消除碰撞。

内容的提问来源于stack exchange，提问作者greg04