native_client_sdk/src/examples/api/graphics_3d/matrix.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /** @file matrix.cc
   6  * Implements simple matrix manipulation functions.
   7  */
   8
   9 //-----------------------------------------------------------------------------
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include "matrix.h"
  13 #define deg_to_rad(x) (x * (M_PI / 180.0f))
  14
  15 void glhFrustumf2(Matrix_t mat,
  16                   GLfloat left,
  17                   GLfloat right,
  18                   GLfloat bottom,
  19                   GLfloat top,
  20                   GLfloat znear,
  21                   GLfloat zfar) {
  22   float temp, temp2, temp3, temp4;
  23   temp = 2.0f * znear;
  24   temp2 = right - left;
  25   temp3 = top - bottom;
  26   temp4 = zfar - znear;
  27   mat[0] = temp / temp2;
  28   mat[1] = 0.0f;
  29   mat[2] = 0.0f;
  30   mat[3] = 0.0f;
  31   mat[4] = 0.0f;
  32   mat[5] = temp / temp3;
  33   mat[6] = 0.0f;
  34   mat[7] = 0.0f;
  35   mat[8] = (right + left) / temp2;
  36   mat[9] = (top + bottom) / temp3;
  37   mat[10] = (-zfar - znear) / temp4;
  38   mat[11] = -1.0f;
  39   mat[12] = 0.0f;
  40   mat[13] = 0.0f;
  41   mat[14] = (-temp * zfar) / temp4;
  42   mat[15] = 0.0f;
  43 }
  44
  45 void glhPerspectivef2(Matrix_t mat,
  46                       GLfloat fovyInDegrees,
  47                       GLfloat aspectRatio,
  48                       GLfloat znear,
  49                       GLfloat zfar) {
  50   float ymax, xmax;
  51   ymax = znear * tanf(fovyInDegrees * 3.14f / 360.0f);
  52   xmax = ymax * aspectRatio;
  53   glhFrustumf2(mat, -xmax, xmax, -ymax, ymax, znear, zfar);
  54 }
  55
  56 void identity_matrix(Matrix_t mat) {
  57   memset(mat, 0, sizeof(Matrix_t));
  58   mat[0] = 1.0;
  59   mat[5] = 1.0;
  60   mat[10] = 1.0;
  61   mat[15] = 1.0;
  62 }
  63
  64 void multiply_matrix(const Matrix_t a, const Matrix_t b, Matrix_t mat) {
  65   // Generate to a temporary first in case the output matrix and input
  66   // matrix are the same.
  67   Matrix_t out;
  68
  69   out[0] = a[0] * b[0] + a[4] * b[1] + a[8] * b[2] + a[12] * b[3];
  70   out[1] = a[1] * b[0] + a[5] * b[1] + a[9] * b[2] + a[13] * b[3];
  71   out[2] = a[2] * b[0] + a[6] * b[1] + a[10] * b[2] + a[14] * b[3];
  72   out[3] = a[3] * b[0] + a[7] * b[1] + a[11] * b[2] + a[15] * b[3];
  73
  74   out[4] = a[0] * b[4] + a[4] * b[5] + a[8] * b[6] + a[12] * b[7];
  75   out[5] = a[1] * b[4] + a[5] * b[5] + a[9] * b[6] + a[13] * b[7];
  76   out[6] = a[2] * b[4] + a[6] * b[5] + a[10] * b[6] + a[14] * b[7];
  77   out[7] = a[3] * b[4] + a[7] * b[5] + a[11] * b[6] + a[15] * b[7];
  78
  79   out[8] = a[0] * b[8] + a[4] * b[9] + a[8] * b[10] + a[12] * b[11];
  80   out[9] = a[1] * b[8] + a[5] * b[9] + a[9] * b[10] + a[13] * b[11];
  81   out[10] = a[2] * b[8] + a[6] * b[9] + a[10] * b[10] + a[14] * b[11];
  82   out[11] = a[3] * b[8] + a[7] * b[9] + a[11] * b[10] + a[15] * b[11];
  83
  84   out[12] = a[0] * b[12] + a[4] * b[13] + a[8] * b[14] + a[12] * b[15];
  85   out[13] = a[1] * b[12] + a[5] * b[13] + a[9] * b[14] + a[13] * b[15];
  86   out[14] = a[2] * b[12] + a[6] * b[13] + a[10] * b[14] + a[14] * b[15];
  87   out[15] = a[3] * b[12] + a[7] * b[13] + a[11] * b[14] + a[15] * b[15];
  88
  89   memcpy(mat, out, sizeof(Matrix_t));
  90 }
  91
  92 void rotate_x_matrix(GLfloat x_rad, Matrix_t mat) {
  93   identity_matrix(mat);
  94   mat[5] = cosf(x_rad);
  95   mat[6] = -sinf(x_rad);
  96   mat[9] = -mat[6];
  97   mat[10] = mat[5];
  98 }
  99
 100 void rotate_y_matrix(GLfloat y_rad, Matrix_t mat) {
 101   identity_matrix(mat);
 102   mat[0] = cosf(y_rad);
 103   mat[2] = sinf(y_rad);
 104   mat[8] = -mat[2];
 105   mat[10] = mat[0];
 106 }
 107
 108 void rotate_z_matrix(GLfloat z_rad, Matrix_t mat) {
 109   identity_matrix(mat);
 110   mat[0] = cosf(z_rad);
 111   mat[1] = sinf(z_rad);
 112   mat[4] = -mat[1];
 113   mat[5] = mat[0];
 114 }
 115
 116 void rotate_matrix(GLfloat x_deg, GLfloat y_deg, GLfloat z_deg, Matrix_t mat) {
 117   GLfloat x_rad = (GLfloat) deg_to_rad(x_deg);
 118   GLfloat y_rad = (GLfloat) deg_to_rad(y_deg);
 119   GLfloat z_rad = (GLfloat) deg_to_rad(z_deg);
 120
 121   Matrix_t x_matrix;
 122   Matrix_t y_matrix;
 123   Matrix_t z_matrix;
 124
 125   rotate_x_matrix(x_rad, x_matrix);
 126   rotate_y_matrix(y_rad, y_matrix);
 127   rotate_z_matrix(z_rad, z_matrix);
 128
 129   Matrix_t xy_matrix;
 130   multiply_matrix(y_matrix, x_matrix, xy_matrix);
 131   multiply_matrix(z_matrix, xy_matrix, mat);
 132 }
 133
 134 void translate_matrix(GLfloat x, GLfloat y, GLfloat z, Matrix_t mat) {
 135   identity_matrix(mat);
 136   mat[12] += x;
 137   mat[13] += y;
 138   mat[14] += z;
 139 }