1// OpenGL ES 2.0 code
2
3#include <nativehelper/jni.h>
4#define LOG_TAG "GL2JNI gl_code.cpp"
5#include <utils/Log.h>
6
7#include <EGL/egl.h>
8#include <GLES2/gl2.h>
9#include <GLES2/gl2ext.h>
10
11#include <stdio.h>
12#include <stdlib.h>
13#include <math.h>
14
15static void printGLString(const char *name, GLenum s) {
16    const char *v = (const char *) glGetString(s);
17    ALOGI("GL %s = %s\n", name, v);
18}
19
20static void checkGlError(const char* op) {
21    for (GLint error = glGetError(); error; error
22            = glGetError()) {
23        ALOGI("after %s() glError (0x%x)\n", op, error);
24    }
25}
26
27static const char gVertexShader[] = "attribute vec4 vPosition;\n"
28    "void main() {\n"
29    "  gl_Position = vPosition;\n"
30    "}\n";
31
32static const char gFragmentShader[] = "precision mediump float;\n"
33    "void main() {\n"
34    "  gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);\n"
35    "}\n";
36
37GLuint loadShader(GLenum shaderType, const char* pSource) {
38    GLuint shader = glCreateShader(shaderType);
39    if (shader) {
40        glShaderSource(shader, 1, &pSource, NULL);
41        glCompileShader(shader);
42        GLint compiled = 0;
43        glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
44        if (!compiled) {
45            GLint infoLen = 0;
46            glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);
47            if (infoLen) {
48                char* buf = (char*) malloc(infoLen);
49                if (buf) {
50                    glGetShaderInfoLog(shader, infoLen, NULL, buf);
51                    ALOGE("Could not compile shader %d:\n%s\n",
52                            shaderType, buf);
53                    free(buf);
54                }
55                glDeleteShader(shader);
56                shader = 0;
57            }
58        }
59    }
60    return shader;
61}
62
63GLuint createProgram(const char* pVertexSource, const char* pFragmentSource) {
64    GLuint vertexShader = loadShader(GL_VERTEX_SHADER, pVertexSource);
65    if (!vertexShader) {
66        return 0;
67    }
68
69    GLuint pixelShader = loadShader(GL_FRAGMENT_SHADER, pFragmentSource);
70    if (!pixelShader) {
71        return 0;
72    }
73
74    GLuint program = glCreateProgram();
75    if (program) {
76        glAttachShader(program, vertexShader);
77        checkGlError("glAttachShader");
78        glAttachShader(program, pixelShader);
79        checkGlError("glAttachShader");
80        glLinkProgram(program);
81        GLint linkStatus = GL_FALSE;
82        glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);
83        if (linkStatus != GL_TRUE) {
84            GLint bufLength = 0;
85            glGetProgramiv(program, GL_INFO_LOG_LENGTH, &bufLength);
86            if (bufLength) {
87                char* buf = (char*) malloc(bufLength);
88                if (buf) {
89                    glGetProgramInfoLog(program, bufLength, NULL, buf);
90                    ALOGE("Could not link program:\n%s\n", buf);
91                    free(buf);
92                }
93            }
94            glDeleteProgram(program);
95            program = 0;
96        }
97    }
98    return program;
99}
100
101GLuint gProgram;
102GLuint gvPositionHandle;
103
104bool setupGraphics(int w, int h) {
105    printGLString("Version", GL_VERSION);
106    printGLString("Vendor", GL_VENDOR);
107    printGLString("Renderer", GL_RENDERER);
108    printGLString("Extensions", GL_EXTENSIONS);
109
110    ALOGI("setupGraphics(%d, %d)", w, h);
111    gProgram = createProgram(gVertexShader, gFragmentShader);
112    if (!gProgram) {
113        ALOGE("Could not create program.");
114        return false;
115    }
116    gvPositionHandle = glGetAttribLocation(gProgram, "vPosition");
117    checkGlError("glGetAttribLocation");
118    ALOGI("glGetAttribLocation(\"vPosition\") = %d\n",
119            gvPositionHandle);
120
121    glViewport(0, 0, w, h);
122    checkGlError("glViewport");
123    return true;
124}
125
126const GLfloat gTriangleVertices[] = { 0.0f, 0.5f, -0.5f, -0.5f,
127        0.5f, -0.5f };
128
129void renderFrame() {
130    static float grey;
131    grey += 0.01f;
132    if (grey > 1.0f) {
133        grey = 0.0f;
134    }
135    glClearColor(grey, grey, grey, 1.0f);
136    checkGlError("glClearColor");
137    glClear( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
138    checkGlError("glClear");
139
140    glUseProgram(gProgram);
141    checkGlError("glUseProgram");
142
143    glVertexAttribPointer(gvPositionHandle, 2, GL_FLOAT, GL_FALSE, 0, gTriangleVertices);
144    checkGlError("glVertexAttribPointer");
145    glEnableVertexAttribArray(gvPositionHandle);
146    checkGlError("glEnableVertexAttribArray");
147    glDrawArrays(GL_TRIANGLES, 0, 3);
148    checkGlError("glDrawArrays");
149}
150
151extern "C" {
152    JNIEXPORT void JNICALL Java_com_android_gl2jni_GL2JNILib_init(JNIEnv * env, jobject obj,  jint width, jint height);
153    JNIEXPORT void JNICALL Java_com_android_gl2jni_GL2JNILib_step(JNIEnv * env, jobject obj);
154};
155
156JNIEXPORT void JNICALL Java_com_android_gl2jni_GL2JNILib_init(JNIEnv * env, jobject obj,  jint width, jint height)
157{
158    setupGraphics(width, height);
159}
160
161JNIEXPORT void JNICALL Java_com_android_gl2jni_GL2JNILib_step(JNIEnv * env, jobject obj)
162{
163    renderFrame();
164}
165
166