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# 脚踏实地

float4x4 LookAtMatrix(float3 eyePosition, float3 lookAt, float3 up)
{
float3 zaxis = normalize(lookAt - eyePosition);
float3 yaxis = normalize(up);
float3 xaxis = normalize(cross(yaxis, zaxis));
yaxis = normalize(cross(zaxis, xaxis));

float4x4 result = float4x4(xaxis.x, yaxis.x, zaxis.x, 0.0,
xaxis.y, yaxis.y, zaxis.y, 0.0,
xaxis.z, yaxis.z, zaxis.z, 0.0,
-dot(xaxis, eyePosition), -dot(yaxis, eyePosition), -dot(zaxis, eyePosition), 1.0);

return result;
}
#define MATH_PI_DIV_180  0.0174532925
float4x4 DxPorjMatrix(float fov_y, float aspect, float zNear, float zFar)
{
// Left Hand
float f_n = 1.0f / (zFar - zNear);
float yScale = 1.0 / tan(MATH_PI_DIV_180 * (fov_y) * 0.5f);
float xScale = yScale / aspect;
float4x4 result = float4x4(xScale, 0.0, 0.0, 0.0,
0.0, yScale, 0.0, 0.0,
0.0, 0.0, zFar*f_n, 1.0,
0.0, 0.0, -zNear * zFar * f_n, 1.0);
return result;
}

biliner 插值
posted on 2015-10-24 10:38 LSH 阅读(75) 评论(0)  编辑 收藏 引用