void glOrtho(GLdouble left, GLdouble right, GLdouble bottom, GLdouble top, GLdouble zNear, GLdouble zFar) {
matrix_4x4 mp;
m4x4_zeros(&mp);
int mode = ctr_state.matrix_current;
int depth = ctr_state.matrix_depth[mode];
matrix_4x4 *mat = &ctr_state.matrix[mode][depth];
if (!mat) {
return;
}
// Build standard orthogonal projection matrix
mp.r[0].x = 2.0f / (right - left);
mp.r[0].w = (left + right) / (left - right);
mp.r[1].y = 2.0f / (top - bottom);
mp.r[1].w = (bottom + top) / (bottom - top);
mp.r[2].z = 2.0f / (zNear - zFar);
mp.r[2].w = (zFar + zNear) / (zFar - zNear);
mp.r[3].w = 1.0f;
// Fix depth range to [-1, 0]
matrix_4x4 mp2, mp3;
m4x4_identity(&mp2);
mp2.r[2].z = 0.5;
mp2.r[2].w = -0.5;
m4x4_multiply(&mp3, &mp2, &mp);
// Fix the 3DS screens' orientation by swapping the X and Y axis
m4x4_identity(&mp2);
mp2.r[0].x = 0.0;
mp2.r[0].y = 1.0;
mp2.r[1].x = -1.0; // flipped
mp2.r[1].y = 0.0;
m4x4_multiply(mat, &mp2, &mp3);
}
void m4x4_ortho_tilt(matrix_4x4* mtx, float left, float right, float bottom, float top, float near, float far)
{
matrix_4x4 mp;
m4x4_zeros(&mp);
// Build standard orthogonal projection matrix
mp.r[0].x = 2.0f / (right - left);
mp.r[0].w = (left + right) / (left - right);
mp.r[1].y = 2.0f / (top - bottom);
mp.r[1].w = (bottom + top) / (bottom - top);
mp.r[2].z = 2.0f / (near - far);
mp.r[2].w = (far + near) / (far - near);
mp.r[3].w = 1.0f;
// Fix depth range to [-1, 0]
matrix_4x4 mp2, mp3;
m4x4_identity(&mp2);
mp2.r[2].z = 0.5;
mp2.r[2].w = -0.5;
m4x4_multiply(&mp3, &mp2, &mp);
// Fix the 3DS screens' orientation by swapping the X and Y axis
m4x4_identity(&mp2);
mp2.r[0].x = 0.0;
mp2.r[0].y = 1.0;
mp2.r[1].x = -1.0; // flipped
mp2.r[1].y = 0.0;
m4x4_multiply(mtx, &mp2, &mp3);
}
void m4x4_rotate(matrix_4x4* mtx, float angle, float x, float y, float z, bool bRightSide)
{
float axis[3];
float sine = sinf(angle);
float cosine = cosf(angle);
float one_minus_cosine = 1.0f - cosine;
matrix_4x4 rm, om;
vector_4f vec = { { 1.0f, z, y, x } };
v4f_norm4(&vec);
axis[0] = vec.x;
axis[1] = vec.y;
axis[2] = vec.z;
m4x4_zeros(&rm);
rm.r[0].x = cosine + (one_minus_cosine * axis[0] * axis[0]);
rm.r[0].y = (one_minus_cosine * axis[0] * axis[1]) - (axis[2] * sine);
rm.r[0].z = (one_minus_cosine * axis[0] * axis[2]) + (axis[1] * sine);
rm.r[1].x = (one_minus_cosine * axis[0] * axis[1]) + (axis[2] * sine);
rm.r[1].y = cosine + (one_minus_cosine * axis[1] * axis[1]);
rm.r[1].z = (one_minus_cosine * axis[1] * axis[2]) - (axis[0] * sine);
rm.r[2].x = (one_minus_cosine * axis[0] * axis[2]) - (axis[1] * sine);
rm.r[2].y = (one_minus_cosine * axis[1] * axis[2]) + (axis[0] * sine);
rm.r[2].z = cosine + (one_minus_cosine * axis[2] * axis[2]);
rm.r[3].w = 1.0f;
if (bRightSide) m4x4_multiply(&om, mtx, &rm);
else m4x4_multiply(&om, &rm, mtx);
m4x4_copy(mtx, &om);
}
void m4x4_rotate_z(matrix_4x4* mtx, float angle, bool bRightSide)
{
matrix_4x4 rm, om;
float cosAngle = cosf(angle);
float sinAngle = sinf(angle);
m4x4_zeros(&rm);
rm.m[0] = cosAngle;
rm.m[1] = sinAngle;
rm.m[4] = -sinAngle;
rm.m[5] = cosAngle;
rm.m[10] = 1.0f;
rm.m[15] = 1.0f;
if (bRightSide) m4x4_multiply(&om, mtx, &rm);
else m4x4_multiply(&om, &rm, mtx);
m4x4_copy(mtx, &om);
}
void m4x4_rotate_z(matrix_4x4* mtx, float angle, bool bRightSide)
{
matrix_4x4 rm, om;
float cosAngle = cosf(angle);
float sinAngle = sinf(angle);
m4x4_zeros(&rm);
rm.r[0].x = cosAngle;
rm.r[0].y = sinAngle;
rm.r[1].x = -sinAngle;
rm.r[1].y = cosAngle;
rm.r[2].z = 1.0f;
rm.r[3].w = 1.0f;
if (bRightSide) m4x4_multiply(&om, mtx, &rm);
else m4x4_multiply(&om, &rm, mtx);
m4x4_copy(mtx, &om);
}
void m4x4_persp_tilt(matrix_4x4* mtx, float fovx, float invaspect, float near, float far)
{
// Notes:
// We are passed "fovy" and the "aspect ratio". However, the 3DS screens are sideways,
// and so are these parameters -- in fact, they are actually the fovx and the inverse
// of the aspect ratio. Therefore the formula for the perspective projection matrix
// had to be modified to be expressed in these terms instead.
// Notes:
// fovx = 2 atan(tan(fovy/2)*w/h)
// fovy = 2 atan(tan(fovx/2)*h/w)
// invaspect = h/w
// a0,0 = h / (w*tan(fovy/2)) =
// = h / (w*tan(2 atan(tan(fovx/2)*h/w) / 2)) =
// = h / (w*tan( atan(tan(fovx/2)*h/w) )) =
// = h / (w * tan(fovx/2)*h/w) =
// = 1 / tan(fovx/2)
// a1,1 = 1 / tan(fovy/2) = (...) = w / (h*tan(fovx/2))
float fovx_tan = tanf(fovx / 2);
matrix_4x4 mp;
m4x4_zeros(&mp);
// Build standard perspective projection matrix
mp.r[0].x = 1.0f / fovx_tan;
mp.r[1].y = 1.0f / (fovx_tan*invaspect);
mp.r[2].z = (near + far) / (near - far);
mp.r[2].w = (2 * near * far) / (near - far);
mp.r[3].z = -1.0f;
// Fix depth range to [-1, 0]
matrix_4x4 mp2;
m4x4_identity(&mp2);
mp2.r[2].z = 0.5;
mp2.r[2].w = -0.5;
m4x4_multiply(mtx, &mp2, &mp);
// Rotate the matrix one quarter of a turn CCW in order to fix the 3DS screens' orientation
m4x4_rotate_z(mtx, M_PI / 2, true);
}
void m4x4_identity(matrix_4x4* out)
{
m4x4_zeros(out);
out->m[0] = out->m[5] = out->m[10] = out->m[15] = 1.0f;
}
void m4x4_identity(matrix_4x4* out)
{
m4x4_zeros(out);
out->r[0].x = out->r[1].y = out->r[2].z = out->r[3].w = 1.0f;
}
