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// OpenGL ES 1.0 code
#include <nativehelper/jni.h>
#define LOG_TAG "GLJNI gl_code.cpp"
#include <utils/Log.h>
#include <GLES/gl.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
GLuint texture;
GLfloat background;
#define FIXED_ONE 0x10000
static void printGLString(const char *name, GLenum s) {
const char *v = (const char *) glGetString(s);
LOGI("GL %s = %s\n", name, v);
}
static void gluLookAt(float eyeX, float eyeY, float eyeZ,
float centerX, float centerY, float centerZ, float upX, float upY,
float upZ)
{
// See the OpenGL GLUT documentation for gluLookAt for a description
// of the algorithm. We implement it in a straightforward way:
float fx = centerX - eyeX;
float fy = centerY - eyeY;
float fz = centerZ - eyeZ;
// Normalize f
float rlf = 1.0f / sqrtf(fx*fx + fy*fy + fz*fz);
fx *= rlf;
fy *= rlf;
fz *= rlf;
// Normalize up
float rlup = 1.0f / sqrtf(upX*upX + upY*upY + upZ*upZ);
upX *= rlup;
upY *= rlup;
upZ *= rlup;
// compute s = f x up (x means "cross product")
float sx = fy * upZ - fz * upY;
float sy = fz * upX - fx * upZ;
float sz = fx * upY - fy * upX;
// compute u = s x f
float ux = sy * fz - sz * fy;
float uy = sz * fx - sx * fz;
float uz = sx * fy - sy * fx;
float m[16] ;
m[0] = sx;
m[1] = ux;
m[2] = -fx;
m[3] = 0.0f;
m[4] = sy;
m[5] = uy;
m[6] = -fy;
m[7] = 0.0f;
m[8] = sz;
m[9] = uz;
m[10] = -fz;
m[11] = 0.0f;
m[12] = 0.0f;
m[13] = 0.0f;
m[14] = 0.0f;
m[15] = 1.0f;
glMultMatrixf(m);
glTranslatef(-eyeX, -eyeY, -eyeZ);
}
void init_scene(int width, int height)
{
printGLString("Version", GL_VERSION);
printGLString("Vendor", GL_VENDOR);
printGLString("Renderer", GL_RENDERER);
printGLString("Extensions", GL_EXTENSIONS);
glDisable(GL_DITHER);
glEnable(GL_CULL_FACE);
float ratio = width / height;
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustumf(-ratio, ratio, -1, 1, 1, 10);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(
0, 0, 3, // eye
0, 0, 0, // center
0, 1, 0); // up
glEnable(GL_TEXTURE_2D);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
}
void create_texture()
{
const unsigned int on = 0xff0000ff;
const unsigned int off = 0xffffffff;
const unsigned int pixels[] =
{
on, off, on, off, on, off, on, off,
off, on, off, on, off, on, off, on,
on, off, on, off, on, off, on, off,
off, on, off, on, off, on, off, on,
on, off, on, off, on, off, on, off,
off, on, off, on, off, on, off, on,
on, off, on, off, on, off, on, off,
off, on, off, on, off, on, off, on,
};
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 8, 8, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
}
extern "C" {
JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_init(JNIEnv * env, jobject obj, jint width, jint height);
JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_step(JNIEnv * env, jobject obj);
JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_changeBackground(JNIEnv * env, jobject obj);
};
JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_init(JNIEnv * env, jobject obj, jint width, jint height)
{
init_scene(width, height);
create_texture();
}
JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_step(JNIEnv * env, jobject obj)
{
const GLfloat vertices[] = {
-1, -1, 0,
1, -1, 0,
1, 1, 0,
-1, 1, 0
};
const GLfixed texCoords[] = {
0, 0,
FIXED_ONE, 0,
FIXED_ONE, FIXED_ONE,
0, FIXED_ONE
};
const GLushort quadIndices[] = { 0, 1, 2, 0, 2, 3 };
glVertexPointer(3, GL_FLOAT, 0, vertices);
glTexCoordPointer(2, GL_FIXED, 0, texCoords);
int nelem = sizeof(quadIndices)/sizeof(quadIndices[0]);
static float grey;
grey += 0.01f;
if (grey > 1.0f) {
grey = 0.0f;
}
glClearColor(background, grey, grey, 1.0f);
glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
glDrawElements(GL_TRIANGLES, nelem, GL_UNSIGNED_SHORT, quadIndices);
}
JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_changeBackground(JNIEnv * env, jobject obj)
{
background = 1.0f - background;
}
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