我正在写一个简单的光线着色器,我正试图用一个立方体和一些代表圆点的球体来制作一个骰子。球体是正确的,但立方体的两侧是x,y和z轴。立方体以0,0,0为中心。
我检查过顶点的坐标是否正确。我假设我的射线计算是正确的,因为球体位于正确的位置。
以下是光线计算的代码
Ray Image::RayThruPixel(float i, float j)
{
float alpha = m_tanFOVx * ((j - m_halfWidth) / m_halfWidth);
float beta = m_tanFOVy * ((m_halfHeight - i) / m_halfHeight);
vec3 *coordFrame = m_camera.CoordFrame();
vec3 p1 = (coordFrame[U_VEC] * alpha) + (coordFrame[V_VEC] * beta) - coordFrame[W_VEC];
return Ray(m_camera.Eye(), p1);
}
其中m_tanFOVx为tan(FOVx / 2),m_tanFOVy为tan(FOVy / 2),FOVx和FOVy为弧度。
要找到光线和三角形的交点,我的代码如下:
bool Triangle::Intersection(Ray ray, float &fDistance)
{
static float epsilon = 0.000001;
bool bHit = false;
float fMinDist(10000000);
float divisor = glm::dot(ray.p1, normal);
// if divisor == 0 then the ray is parallel with the triangle
if(divisor > -epsilon && divisor < epsilon)
{
bHit = false;
}
else
{
float t = (glm::dot(v0, normal) - glm::dot(ray.p0, normal)) / divisor;
if(t > 0)
{
vec3 P = ray.p0 + (ray.p1 * t);
vec3 v2 = P - m_vertexA;
v0 = m_vertexB - m_vertexA;
v1 = m_vertexC - m_vertexA;
normal = glm::normalize(glm::cross(v0, v1));
d00 = glm::dot(v0, v0);
d01 = glm::dot(v0, v1);
d11 = glm::dot(v1, v1);
denom = d00 * d11 - d01 * d01;
float d20 = glm::dot(v2, v0);
float d21 = glm::dot(v2, v1);
float alpha = (d11 * d20 - d01 * d21) / denom;
float beta = (d00 * d21 - d01 * d20) / denom;
float gamma = 1.0 - alpha - beta;
vec3 testP = alpha * m_vertexA + beta * m_vertexB + gamma * m_vertexC;
if((alpha >= 0 ) &&
(beta >= 0) &&
(alpha + beta <= 1))
{
bHit = true;
fDistance = t;
}
}
}
return bHit;
}