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https://github.com/bulletphysics/bullet3
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117 lines
3.3 KiB
C++
117 lines
3.3 KiB
C++
// Copyright (c) 2011 The Native Client Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "transforms.h"
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#include <math.h>
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#include <string.h>
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#include <GLES2/gl2.h>
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namespace transform_4x4 {
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static const GLfloat kPI = 3.1415926535897932384626433832795f;
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void Translate(GLfloat* m, GLfloat tx, GLfloat ty, GLfloat tz) {
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m[12] += (m[0] * tx + m[4] * ty + m[8] * tz);
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m[13] += (m[1] * tx + m[5] * ty + m[9] * tz);
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m[14] += (m[2] * tx + m[6] * ty + m[10] * tz);
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m[15] += (m[3] * tx + m[7] * ty + m[11] * tz);
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}
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void Frustum(GLfloat* m,
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GLfloat left,
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GLfloat right,
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GLfloat bottom,
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GLfloat top,
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GLfloat near_z,
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GLfloat far_z) {
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GLfloat delta_x = right - left;
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GLfloat delta_y = top - bottom;
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GLfloat delta_z = far_z - near_z;
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GLfloat frustum[16];
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if ((near_z <= 0.0f) || (far_z <= 0.0f) ||
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(delta_x <= 0.0f) || (delta_y <= 0.0f) || (delta_z <= 0.0f))
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return;
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frustum[0] = 2.0f * near_z / delta_x;
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frustum[1] = frustum[2] = frustum[3] = 0.0f;
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frustum[5] = 2.0f * near_z / delta_y;
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frustum[4] = frustum[6] = frustum[7] = 0.0f;
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frustum[8] = (right + left) / delta_x;
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frustum[9] = (top + bottom) / delta_y;
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frustum[10] = -(near_z + far_z) / delta_z;
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frustum[11] = -1.0f;
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frustum[14] = -2.0f * near_z * far_z / delta_z;
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frustum[12] = frustum[13] = frustum[15] = 0.0f;
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transform_4x4::Multiply(m, frustum, m);
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}
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void Perspective(GLfloat* m,
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GLfloat fovy,
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GLfloat aspect,
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GLfloat near_z,
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GLfloat far_z) {
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GLfloat frustum_w, frustum_h;
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frustum_h = tanf((fovy * 0.5f) / 180.0f * kPI) * near_z;
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frustum_w = frustum_h * aspect;
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transform_4x4::Frustum(m, -frustum_w, frustum_w, -frustum_h, frustum_h,
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near_z, far_z);
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}
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void Multiply(GLfloat *m, GLfloat *a, GLfloat* b) {
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GLfloat tmp[16];
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// tmp = a . b
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GLfloat a0, a1, a2, a3;
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a0 = a[0];
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a1 = a[1];
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a2 = a[2];
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a3 = a[3];
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tmp[0] = a0 * b[0] + a1 * b[4] + a2 * b[8] + a3 * b[12];
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tmp[1] = a0 * b[1] + a1 * b[5] + a2 * b[9] + a3 * b[13];
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tmp[2] = a0 * b[2] + a1 * b[6] + a2 * b[10] + a3 * b[14];
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tmp[3] = a0 * b[3] + a1 * b[7] + a2 * b[11] + a3 * b[15];
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a0 = a[4];
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a1 = a[5];
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a2 = a[6];
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a3 = a[7];
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tmp[4] = a0 * b[0] + a1 * b[4] + a2 * b[8] + a3 * b[12];
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tmp[5] = a0 * b[1] + a1 * b[5] + a2 * b[9] + a3 * b[13];
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tmp[6] = a0 * b[2] + a1 * b[6] + a2 * b[10] + a3 * b[14];
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tmp[7] = a0 * b[3] + a1 * b[7] + a2 * b[11] + a3 * b[15];
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a0 = a[8];
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a1 = a[9];
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a2 = a[10];
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a3 = a[11];
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tmp[8] = a0 * b[0] + a1 * b[4] + a2 * b[8] + a3 * b[12];
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tmp[9] = a0 * b[1] + a1 * b[5] + a2 * b[9] + a3 * b[13];
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tmp[10] = a0 * b[2] + a1 * b[6] + a2 * b[10] + a3 * b[14];
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tmp[11] = a0 * b[3] + a1 * b[7] + a2 * b[11] + a3 * b[15];
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a0 = a[12];
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a1 = a[13];
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a2 = a[14];
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a3 = a[15];
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tmp[12] = a0 * b[0] + a1 * b[4] + a2 * b[8] + a3 * b[12];
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tmp[13] = a0 * b[1] + a1 * b[5] + a2 * b[9] + a3 * b[13];
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tmp[14] = a0 * b[2] + a1 * b[6] + a2 * b[10] + a3 * b[14];
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tmp[15] = a0 * b[3] + a1 * b[7] + a2 * b[11] + a3 * b[15];
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memcpy(m, tmp, sizeof(GLfloat) * 4 * 4);
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}
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void LoadIdentity(GLfloat* m) {
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memset(m, 0, sizeof(GLfloat) * 4 * 4);
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m[0] = m[5] = m[10] = m[15] = 1.0f;
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}
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} // namespace transform_4x4
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