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FreeGLUT-Vita/progs/demos/shapes/glmatrix.c
2020-10-29 22:28:16 +03:00

220 lines
5.8 KiB
C

#include <string.h>
#define _USE_MATH_DEFINES
#include <math.h>
#include "glmatrix.h"
#ifndef M_PI
#define M_PI 3.141592653589793
#endif
#define MMODE_IDX(x) ((x) - GL_MODELVIEW)
#define MAT_STACK_SIZE 32
#define MAT_IDENT {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1}
static int mm_idx = 0;
static float mat_stack[3][MAT_STACK_SIZE][16] = {{MAT_IDENT}, {MAT_IDENT}, {MAT_IDENT}};
static int stack_top[3];
void gl_matrix_mode(int mm)
{
mm_idx = MMODE_IDX(mm);
}
void gl_push_matrix(void)
{
int top = stack_top[mm_idx];
memcpy(mat_stack[mm_idx][top + 1], mat_stack[mm_idx][top], 16 * sizeof(float));
stack_top[mm_idx]++;
}
void gl_pop_matrix(void)
{
stack_top[mm_idx]--;
}
void gl_load_identity(void)
{
static const float idmat[] = MAT_IDENT;
int top = stack_top[mm_idx];
float *mat = mat_stack[mm_idx][top];
memcpy(mat, idmat, sizeof idmat);
}
void gl_load_matrixf(const float *m)
{
int top = stack_top[mm_idx];
float *mat = mat_stack[mm_idx][top];
memcpy(mat, m, 16 * sizeof *mat);
}
#define M4(i, j) ((i << 2) + j)
void gl_mult_matrixf(const float *m2)
{
int i, j;
int top = stack_top[mm_idx];
float *m1 = mat_stack[mm_idx][top];
float res[16];
for(i=0; i<4; i++) {
for(j=0; j<4; j++) {
res[M4(i,j)] = m1[M4(i,0)] * m2[M4(0,j)] +
m1[M4(i,1)] * m2[M4(1,j)] +
m1[M4(i,2)] * m2[M4(2,j)] +
m1[M4(i,3)] * m2[M4(3,j)];
}
}
memcpy(m1, res, sizeof res);
}
void gl_translatef(float x, float y, float z)
{
float mat[] = MAT_IDENT;
mat[12] = x;
mat[13] = y;
mat[14] = z;
gl_mult_matrixf(mat);
}
void gl_rotatef(float angle, float x, float y, float z)
{
float mat[] = MAT_IDENT;
float angle_rad = (float)M_PI * angle / 180.f;
float sina = (float)sin(angle_rad);
float cosa = (float)cos(angle_rad);
float one_minus_cosa = 1.f - cosa;
float nxsq = x * x;
float nysq = y * y;
float nzsq = z * z;
mat[0] = nxsq + (1.f - nxsq) * cosa;
mat[4] = x * y * one_minus_cosa - z * sina;
mat[8] = x * z * one_minus_cosa + y * sina;
mat[1] = x * y * one_minus_cosa + z * sina;
mat[5] = nysq + (1.f - nysq) * cosa;
mat[9] = y * z * one_minus_cosa - x * sina;
mat[2] = x * z * one_minus_cosa - y * sina;
mat[6] = y * z * one_minus_cosa + x * sina;
mat[10] = nzsq + (1.f - nzsq) * cosa;
gl_mult_matrixf(mat);
}
void gl_scalef(float x, float y, float z)
{
float mat[] = MAT_IDENT;
mat[0] = x;
mat[5] = y;
mat[10] = z;
gl_mult_matrixf(mat);
}
void gl_ortho(float left, float right, float bottom, float top, float znear, float zfar)
{
float mat[] = MAT_IDENT;
float dx = right - left;
float dy = top - bottom;
float dz = zfar - znear;
float tx = -(right + left) / dx;
float ty = -(top + bottom) / dy;
float tz = -(zfar + znear) / dz;
float sx = 2.f / dx;
float sy = 2.f / dy;
float sz = -2.f / dz;
mat[0] = sx;
mat[5] = sy;
mat[10] = sz;
mat[12] = tx;
mat[13] = ty;
mat[14] = tz;
gl_mult_matrixf(mat);
}
void gl_frustum(float left, float right, float bottom, float top, float znear, float zfar)
{
float mat[] = MAT_IDENT;
float dx = right - left;
float dy = top - bottom;
float dz = zfar - znear;
float a = (right + left) / dx;
float b = (top + bottom) / dy;
float c = -(zfar + znear) / dz;
float d = -2.f * zfar * znear / dz;
mat[0] = 2.f * znear / dx;
mat[5] = 2.f * znear / dy;
mat[8] = a;
mat[9] = b;
mat[10] = c;
mat[11] = -1.f;
mat[14] = d;
mat[15] = 0;
gl_mult_matrixf(mat);
}
void glu_perspective(float vfov, float aspect, float znear, float zfar)
{
float vfov_rad = (float)M_PI * vfov / 180.f;
float x = znear * (float)tan(vfov_rad / 2.f);
gl_frustum(-aspect * x, aspect * x, -x, x, znear, zfar);
}
/* return the matrix (16 elements, 4x4 matrix, row-major order */
float* get_matrix(int mm)
{
int idx = MMODE_IDX(mm);
int top = stack_top[idx];
return mat_stack[idx][top];
}
#define M3(i, j) ((i * 3) + j)
static float inv_transpose_result[9];
/* return the inverse transpose of the left-upper 3x3 of a matrix
The returned pointer is only valid until the next time this function is
called, so make a deep copy when you want to keep it around.
*/
float* get_inv_transpose_3x3(int mm)
{
int idx = MMODE_IDX(mm);
int top = stack_top[idx];
float *m1 = mat_stack[idx][top];
float determinant = +m1[M4(0,0)]*(m1[M4(1,1)]*m1[M4(2,2)]-m1[M4(2,1)]*m1[M4(1,2)])
-m1[M4(0,1)]*(m1[M4(1,0)]*m1[M4(2,2)]-m1[M4(1,2)]*m1[M4(2,0)])
+m1[M4(0,2)]*(m1[M4(1,0)]*m1[M4(2,1)]-m1[M4(1,1)]*m1[M4(2,0)]);
float invdet = 1/determinant;
inv_transpose_result[M3(0,0)] = (m1[M4(1,1)]*m1[M4(2,2)]-m1[M4(2,1)]*m1[M4(1,2)])*invdet;
inv_transpose_result[M3(1,0)] = -(m1[M4(0,1)]*m1[M4(2,2)]-m1[M4(0,2)]*m1[M4(2,1)])*invdet;
inv_transpose_result[M3(2,0)] = (m1[M4(0,1)]*m1[M4(1,2)]-m1[M4(0,2)]*m1[M4(1,1)])*invdet;
inv_transpose_result[M3(0,1)] = -(m1[M4(1,0)]*m1[M4(2,2)]-m1[M4(1,2)]*m1[M4(2,0)])*invdet;
inv_transpose_result[M3(1,1)] = (m1[M4(0,0)]*m1[M4(2,2)]-m1[M4(0,2)]*m1[M4(2,0)])*invdet;
inv_transpose_result[M3(2,1)] = -(m1[M4(0,0)]*m1[M4(1,2)]-m1[M4(1,0)]*m1[M4(0,2)])*invdet;
inv_transpose_result[M3(0,2)] = (m1[M4(1,0)]*m1[M4(2,1)]-m1[M4(2,0)]*m1[M4(1,1)])*invdet;
inv_transpose_result[M3(1,2)] = -(m1[M4(0,0)]*m1[M4(2,1)]-m1[M4(2,0)]*m1[M4(0,1)])*invdet;
inv_transpose_result[M3(2,2)] = (m1[M4(0,0)]*m1[M4(1,1)]-m1[M4(1,0)]*m1[M4(0,1)])*invdet;
return inv_transpose_result;
}