Add a new sample named "hello-gl2" that shows how to call OGL ES 2.0 functions

from native code through JNI.

ndk/apps/hello-gl2/project/jni/gl_code.cpp

@@ -0,0 +1,182 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// OpenGL ES 2.0 code
+
+#include <jni.h>
+#include <android/log.h>
+
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+#define  LOG_TAG    "libgl2jni"
+#define  LOGI(...)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
+#define  LOGE(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
+
+static void printGLString(const char *name, GLenum s) {
+    const char *v = (const char *) glGetString(s);
+    LOGI("GL %s = %s\n", name, v);
+}
+
+static void checkGlError(const char* op) {
+    for (GLint error = glGetError(); error; error
+            = glGetError()) {
+        LOGI("after %s() glError (0x%x)\n", op, error);
+    }
+}
+
+static const char gVertexShader[] = "attribute vec4 vPosition;\n"
+    "void main() {\n"
+    "  gl_Position = vPosition;\n"
+    "}\n";
+
+static const char gFragmentShader[] = "precision mediump float;\n"
+    "void main() {\n"
+    "  gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);\n"
+    "}\n";
+
+GLuint loadShader(GLenum shaderType, const char* pSource) {
+    GLuint shader = glCreateShader(shaderType);
+    if (shader) {
+        glShaderSource(shader, 1, &pSource, NULL);
+        glCompileShader(shader);
+        GLint compiled = 0;
+        glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
+        if (!compiled) {
+            GLint infoLen = 0;
+            glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);
+            if (infoLen) {
+                char* buf = (char*) malloc(infoLen);
+                if (buf) {
+                    glGetShaderInfoLog(shader, infoLen, NULL, buf);
+                    LOGE("Could not compile shader %d:\n%s\n",
+                            shaderType, buf);
+                    free(buf);
+                }
+                glDeleteShader(shader);
+                shader = 0;
+            }
+        }
+    }
+    return shader;
+}
+
+GLuint createProgram(const char* pVertexSource, const char* pFragmentSource) {
+    GLuint vertexShader = loadShader(GL_VERTEX_SHADER, pVertexSource);
+    if (!vertexShader) {
+        return 0;
+    }
+
+    GLuint pixelShader = loadShader(GL_FRAGMENT_SHADER, pFragmentSource);
+    if (!pixelShader) {
+        return 0;
+    }
+
+    GLuint program = glCreateProgram();
+    if (program) {
+        glAttachShader(program, vertexShader);
+        checkGlError("glAttachShader");
+        glAttachShader(program, pixelShader);
+        checkGlError("glAttachShader");
+        glLinkProgram(program);
+        GLint linkStatus = GL_FALSE;
+        glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);
+        if (linkStatus != GL_TRUE) {
+            GLint bufLength = 0;
+            glGetProgramiv(program, GL_INFO_LOG_LENGTH, &bufLength);
+            if (bufLength) {
+                char* buf = (char*) malloc(bufLength);
+                if (buf) {
+                    glGetProgramInfoLog(program, bufLength, NULL, buf);
+                    LOGE("Could not link program:\n%s\n", buf);
+                    free(buf);
+                }
+            }
+            glDeleteProgram(program);
+            program = 0;
+        }
+    }
+    return program;
+}
+
+GLuint gProgram;
+GLuint gvPositionHandle;
+
+bool setupGraphics(int w, int h) {
+    printGLString("Version", GL_VERSION);
+    printGLString("Vendor", GL_VENDOR);
+    printGLString("Renderer", GL_RENDERER);
+    printGLString("Extensions", GL_EXTENSIONS);
+
+    LOGI("setupGraphics(%d, %d)", w, h);
+    gProgram = createProgram(gVertexShader, gFragmentShader);
+    if (!gProgram) {
+        LOGE("Could not create program.");
+        return false;
+    }
+    gvPositionHandle = glGetAttribLocation(gProgram, "vPosition");
+    checkGlError("glGetAttribLocation");
+    LOGI("glGetAttribLocation(\"vPosition\") = %d\n",
+            gvPositionHandle);
+
+    glViewport(0, 0, w, h);
+    checkGlError("glViewport");
+    return true;
+}
+
+const GLfloat gTriangleVertices[] = { 0.0f, 0.5f, -0.5f, -0.5f,
+        0.5f, -0.5f };
+
+void renderFrame() {
+    static float grey;
+    grey += 0.01f;
+    if (grey > 1.0f) {
+        grey = 0.0f;
+    }
+    glClearColor(grey, grey, grey, 1.0f);
+    checkGlError("glClearColor");
+    glClear( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
+    checkGlError("glClear");
+
+    glUseProgram(gProgram);
+    checkGlError("glUseProgram");
+
+    glVertexAttribPointer(gvPositionHandle, 2, GL_FLOAT, GL_FALSE, 0, gTriangleVertices);
+    checkGlError("glVertexAttribPointer");
+    glEnableVertexAttribArray(gvPositionHandle);
+    checkGlError("glEnableVertexAttribArray");
+    glDrawArrays(GL_TRIANGLES, 0, 3);
+    checkGlError("glDrawArrays");
+}
+
+extern "C" {
+    JNIEXPORT void JNICALL Java_com_android_gl2jni_GL2JNILib_init(JNIEnv * env, jobject obj,  jint width, jint height);
+    JNIEXPORT void JNICALL Java_com_android_gl2jni_GL2JNILib_step(JNIEnv * env, jobject obj);
+};
+
+JNIEXPORT void JNICALL Java_com_android_gl2jni_GL2JNILib_init(JNIEnv * env, jobject obj,  jint width, jint height)
+{
+    setupGraphics(width, height);
+}
+
+JNIEXPORT void JNICALL Java_com_android_gl2jni_GL2JNILib_step(JNIEnv * env, jobject obj)
+{
+    renderFrame();
+}