////////////////////////////////////////////////////////////////////////////////
// Create Orthographic projection. From Guide to OpenGL ES 2.0
////////////////////////////////////////////////////////////////////////////////
Matrix44 Matrix44::CreateOrtho(float left, float right, float bottom, float top, float nearZ, float farZ)
{
// Get bounds
float deltaX = right - left;
float deltaY = top - bottom;
float deltaZ = farZ - nearZ;
//
Matrix44 ortho;
ortho.SetIndentity();
// Check bad parameters
if ( (deltaX == 0.0f) || (deltaY == 0.0f) || (deltaZ == 0.0f) )
return ortho;
//
ortho.SetIndentity();
ortho.m[0][0] = 2.0f / deltaX;
ortho.m[3][0] = -(right + left) / deltaX;
ortho.m[1][1] = 2.0f / deltaY;
ortho.m[3][1] = -(top + bottom) / deltaY;
ortho.m[2][2] = -2.0f / deltaZ;
ortho.m[3][2] = -(nearZ + farZ) / deltaZ;
return ortho;
}
////////////////////////////////////////////////////////////////////////////////
// Create a frustum projection. From Guide to OpenGL ES 2.0
////////////////////////////////////////////////////////////////////////////////
Matrix44 Matrix44::CreateFrustum(float left, float right, float bottom, float top, float nearZ, float farZ)
{
float deltaX = right - left;
float deltaY = top - bottom;
float deltaZ = farZ - nearZ;
//
Matrix44 frust;
frust.SetIndentity();
if ( (nearZ <= 0.0f) || (farZ <= 0.0f) ||
(deltaX <= 0.0f) || (deltaY <= 0.0f) || (deltaZ <= 0.0f) )
return frust;
frust.m[0][0] = 2.0f * nearZ / deltaX;
frust.m[0][1] = frust.m[0][2] = frust.m[0][3] = 0.0f;
frust.m[1][1] = 2.0f * nearZ / deltaY;
frust.m[1][0] = frust.m[1][2] = frust.m[1][3] = 0.0f;
frust.m[2][0] = (right + left) / deltaX;
frust.m[2][1] = (top + bottom) / deltaY;
frust.m[2][2] = -(nearZ + farZ) / deltaZ;
frust.m[2][3] = -1.0f;
frust.m[3][2] = -2.0f * nearZ * farZ / deltaZ;
frust.m[3][0] = frust.m[3][1] = frust.m[3][3] = 0.0f;
return frust;
}
