이 예제를 모바일 기기에서 실행하면 아래의 그림과 같은 결과를 확인할 수 있다.
package gl.test1;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.Matrix;
import android.os.SystemClock;
import android.util.Log;
/**
* This class implements our custom renderer. Note that the GL10 parameter passed in is unused for OpenGL ES 2.0
* renderers -- the static class GLES20 is used instead.
*/
public class LessonTwoRenderer implements GLSurfaceView.Renderer
{
/** Used for debug logs. */
private static final String TAG = "LessonTwoRenderer";
/**
* Store the model matrix. This matrix is used to move models from object space (where each model can be thought
* of being located at the center of the universe) to world space.
*/
private float[] mModelMatrix = new float[16];
/**
* Store the view matrix. This can be thought of as our camera. This matrix transforms world space to eye space;
* it positions things relative to our eye.
*/
private float[] mViewMatrix = new float[16];
/** Store the projection matrix. This is used to project the scene onto a 2D viewport. */
private float[] mProjectionMatrix = new float[16];
/** Allocate storage for the final combined matrix. This will be passed into the shader program. */
private float[] mMVPMatrix = new float[16];
/**
* Stores a copy of the model matrix specifically for the light position.
*/
private float[] mLightModelMatrix = new float[16];
/** Store our model data in a float buffer. */
private final FloatBuffer mCubePositions;
private final FloatBuffer mCubeColors;
private final FloatBuffer mCubeNormals;
/** This will be used to pass in the transformation matrix. */
private int mMVPMatrixHandle;
/** This will be used to pass in the modelview matrix. */
private int mMVMatrixHandle;
/** This will be used to pass in the light position. */
private int mLightPosHandle;
/** This will be used to pass in model position information. */
private int mPositionHandle;
/** This will be used to pass in model color information. */
private int mColorHandle;
/** This will be used to pass in model normal information. */
private int mNormalHandle;
/** How many bytes per float. */
private final int mBytesPerFloat = 4;
/** Size of the position data in elements. */
private final int mPositionDataSize = 3;
/** Size of the color data in elements. */
private final int mColorDataSize = 4;
/** Size of the normal data in elements. */
private final int mNormalDataSize = 3;
/** Used to hold a light centered on the origin in model space. We need a 4th coordinate so we can get translations to work when
* we multiply this by our transformation matrices. */
private final float[] mLightPosInModelSpace = new float[] {0.0f, 0.0f, 0.0f, 1.0f};
/** Used to hold the current position of the light in world space (after transformation via model matrix). */
private final float[] mLightPosInWorldSpace = new float[4];
/** Used to hold the transformed position of the light in eye space (after transformation via modelview matrix) */
private final float[] mLightPosInEyeSpace = new float[4];
/** This is a handle to our per-vertex cube shading program. */
private int mPerVertexProgramHandle;
/** This is a handle to our light point program. */
private int mPointProgramHandle;
/**
* Initialize the model data.
*/
public LessonTwoRenderer()
{
// Define points for a cube.
// X, Y, Z
final float[] cubePositionData =
{
// In OpenGL counter-clockwise winding is default. This means that when we look at a triangle,
// if the points are counter-clockwise we are looking at the "front". If not we are looking at
// the back. OpenGL has an optimization where all back-facing triangles are culled, since they
// usually represent the backside of an object and aren't visible anyways.
// Front face
-1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, 1.0f,
1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, 1.0f,
1.0f, -1.0f, 1.0f,
1.0f, 1.0f, 1.0f,
// Right face
1.0f, 1.0f, 1.0f,
1.0f, -1.0f, 1.0f,
1.0f, 1.0f, -1.0f,
1.0f, -1.0f, 1.0f,
1.0f, -1.0f, -1.0f,
1.0f, 1.0f, -1.0f,
// Back face
1.0f, 1.0f, -1.0f,
1.0f, -1.0f, -1.0f,
-1.0f, 1.0f, -1.0f,
1.0f, -1.0f, -1.0f,
-1.0f, -1.0f, -1.0f,
-1.0f, 1.0f, -1.0f,
// Left face
-1.0f, 1.0f, -1.0f,
-1.0f, -1.0f, -1.0f,
-1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, -1.0f,
-1.0f, -1.0f, 1.0f,
-1.0f, 1.0f, 1.0f,
// Top face
-1.0f, 1.0f, -1.0f,
-1.0f, 1.0f, 1.0f,
1.0f, 1.0f, -1.0f,
-1.0f, 1.0f, 1.0f,
1.0f, 1.0f, 1.0f,
1.0f, 1.0f, -1.0f,
// Bottom face
1.0f, -1.0f, -1.0f,
1.0f, -1.0f, 1.0f,
-1.0f, -1.0f, -1.0f,
1.0f, -1.0f, 1.0f,
-1.0f, -1.0f, 1.0f,
-1.0f, -1.0f, -1.0f,
};
// R, G, B, A
final float[] cubeColorData =
{
// Front face (red)
1.0f, 0.0f, 0.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f,
// Right face (green)
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
// Back face (blue)
0.0f, 0.0f, 1.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f,
// Left face (yellow)
1.0f, 1.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f, 1.0f,
// Top face (cyan)
0.0f, 1.0f, 1.0f, 1.0f,
0.0f, 1.0f, 1.0f, 1.0f,
0.0f, 1.0f, 1.0f, 1.0f,
0.0f, 1.0f, 1.0f, 1.0f,
0.0f, 1.0f, 1.0f, 1.0f,
0.0f, 1.0f, 1.0f, 1.0f,
// Bottom face (magenta)
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f
};
// X, Y, Z
// The normal is used in light calculations and is a vector which points
// orthogonal to the plane of the surface. For a cube model, the normals
// should be orthogonal to the points of each face.
final float[] cubeNormalData =
{
// Front face
0.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f,
// Right face
1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
// Back face
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, -1.0f,
// Left face
-1.0f, 0.0f, 0.0f,
-1.0f, 0.0f, 0.0f,
-1.0f, 0.0f, 0.0f,
-1.0f, 0.0f, 0.0f,
-1.0f, 0.0f, 0.0f,
-1.0f, 0.0f, 0.0f,
// Top face
0.0f, 1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
// Bottom face
0.0f, -1.0f, 0.0f,
0.0f, -1.0f, 0.0f,
0.0f, -1.0f, 0.0f,
0.0f, -1.0f, 0.0f,
0.0f, -1.0f, 0.0f,
0.0f, -1.0f, 0.0f
};
// Initialize the buffers.
mCubePositions = ByteBuffer.allocateDirect(cubePositionData.length * mBytesPerFloat)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mCubePositions.put(cubePositionData).position(0);
mCubeColors = ByteBuffer.allocateDirect(cubeColorData.length * mBytesPerFloat)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mCubeColors.put(cubeColorData).position(0);
mCubeNormals = ByteBuffer.allocateDirect(cubeNormalData.length * mBytesPerFloat)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mCubeNormals.put(cubeNormalData).position(0);
}
protected String getVertexShader()
{
// TODO: Explain why we normalize the vectors, explain some of the vector math behind it all. Explain what is eye space.
final String vertexShader =
"uniform mat4 u_MVPMatrix; \n" // A constant representing the combined model/view/projection matrix.
+ "uniform mat4 u_MVMatrix; \n" // A constant representing the combined model/view matrix.
+ "uniform vec3 u_LightPos; \n" // The position of the light in eye space.
+ "attribute vec4 a_Position; \n" // Per-vertex position information we will pass in.
+ "attribute vec4 a_Color; \n" // Per-vertex color information we will pass in.
+ "attribute vec3 a_Normal; \n" // Per-vertex normal information we will pass in.
+ "varying vec4 v_Color; \n" // This will be passed into the fragment shader.
+ "void main() \n" // The entry point for our vertex shader.
+ "{ \n"
// Transform the vertex into eye space.
+ " vec3 modelViewVertex = vec3(u_MVMatrix * a_Position); \n"
// Transform the normal's orientation into eye space.
+ " vec3 modelViewNormal = vec3(u_MVMatrix * vec4(a_Normal, 0.0)); \n"
// Will be used for attenuation.
+ " float distance = length(u_LightPos - modelViewVertex); \n"
// Get a lighting direction vector from the light to the vertex.
+ " vec3 lightVector = normalize(u_LightPos - modelViewVertex); \n"
// Calculate the dot product of the light vector and vertex normal. If the normal and light vector are
// pointing in the same direction then it will get max illumination.
+ " float diffuse = max(dot(modelViewNormal, lightVector), 0.1); \n"
// Attenuate the light based on distance.
+ " diffuse = diffuse * (1.0 / (1.0 + (0.25 * distance * distance))); \n"
// Multiply the color by the illumination level. It will be interpolated across the triangle.
+ " v_Color = a_Color * diffuse; \n"
// gl_Position is a special variable used to store the final position.
// Multiply the vertex by the matrix to get the final point in normalized screen coordinates.
+ " gl_Position = u_MVPMatrix * a_Position; \n"
+ "} \n";
return vertexShader;
}
protected String getFragmentShader()
{
final String fragmentShader =
"precision mediump float; \n" // Set the default precision to medium. We don't need as high of a
// precision in the fragment shader.
+ "varying vec4 v_Color; \n" // This is the color from the vertex shader interpolated across the
// triangle per fragment.
+ "void main() \n" // The entry point for our fragment shader.
+ "{ \n"
+ " gl_FragColor = v_Color; \n" // Pass the color directly through the pipeline.
+ "} \n";
return fragmentShader;
}
@Override
public void onSurfaceCreated(GL10 glUnused, EGLConfig config)
{
// Set the background clear color to black.
GLES20.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
// Use culling to remove back faces.
GLES20.glEnable(GLES20.GL_CULL_FACE);
// Enable depth testing
GLES20.glEnable(GLES20.GL_DEPTH_TEST);
// Position the eye in front of the origin.
final float eyeX = 0.0f;
final float eyeY = 0.0f;
final float eyeZ = -0.5f;
// We are looking toward the distance
final float lookX = 0.0f;
final float lookY = 0.0f;
final float lookZ = -5.0f;
// Set our up vector. This is where our head would be pointing were we holding the camera.
final float upX = 0.0f;
final float upY = 1.0f;
final float upZ = 0.0f;
// Set the view matrix. This matrix can be said to represent the camera position.
// NOTE: In OpenGL 1, a ModelView matrix is used, which is a combination of a model and
// view matrix. In OpenGL 2, we can keep track of these matrices separately if we choose.
Matrix.setLookAtM(mViewMatrix, 0, eyeX, eyeY, eyeZ, lookX, lookY, lookZ, upX, upY, upZ);
final String vertexShader = getVertexShader();
final String fragmentShader = getFragmentShader();
final int vertexShaderHandle = compileShader(GLES20.GL_VERTEX_SHADER, vertexShader);
final int fragmentShaderHandle = compileShader(GLES20.GL_FRAGMENT_SHADER, fragmentShader);
mPerVertexProgramHandle = createAndLinkProgram(vertexShaderHandle, fragmentShaderHandle,
new String[] {"a_Position", "a_Color", "a_Normal"});
// Define a simple shader program for our point.
final String pointVertexShader =
"uniform mat4 u_MVPMatrix; \n"
+ "attribute vec4 a_Position; \n"
+ "void main() \n"
+ "{ \n"
+ " gl_Position = u_MVPMatrix \n"
+ " * a_Position; \n"
+ " gl_PointSize = 5.0; \n"
+ "} \n";
final String pointFragmentShader =
"precision mediump float; \n"
+ "void main() \n"
+ "{ \n"
+ " gl_FragColor = vec4(1.0, \n"
+ " 1.0, 1.0, 1.0); \n"
+ "} \n";
final int pointVertexShaderHandle = compileShader(GLES20.GL_VERTEX_SHADER, pointVertexShader);
final int pointFragmentShaderHandle = compileShader(GLES20.GL_FRAGMENT_SHADER, pointFragmentShader);
mPointProgramHandle = createAndLinkProgram(pointVertexShaderHandle, pointFragmentShaderHandle,
new String[] {"a_Position"});
}
@Override
public void onSurfaceChanged(GL10 glUnused, int width, int height)
{
// Set the OpenGL viewport to the same size as the surface.
GLES20.glViewport(0, 0, width, height);
// Create a new perspective projection matrix. The height will stay the same
// while the width will vary as per aspect ratio.
final float ratio = (float) width / height;
final float left = -ratio;
final float right = ratio;
final float bottom = -1.0f;
final float top = 1.0f;
final float near = 1.0f;
final float far = 10.0f;
Matrix.frustumM(mProjectionMatrix, 0, left, right, bottom, top, near, far);
}
@Override
public void onDrawFrame(GL10 glUnused)
{
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);
// Do a complete rotation every 10 seconds.
long time = SystemClock.uptimeMillis() % 10000L;
float angleInDegrees = (360.0f / 10000.0f) * ((int) time);
// Set our per-vertex lighting program.
GLES20.glUseProgram(mPerVertexProgramHandle);
// Set program handles for cube drawing.
mMVPMatrixHandle = GLES20.glGetUniformLocation(mPerVertexProgramHandle, "u_MVPMatrix");
mMVMatrixHandle = GLES20.glGetUniformLocation(mPerVertexProgramHandle, "u_MVMatrix");
mLightPosHandle = GLES20.glGetUniformLocation(mPerVertexProgramHandle, "u_LightPos");
mPositionHandle = GLES20.glGetAttribLocation(mPerVertexProgramHandle, "a_Position");
mColorHandle = GLES20.glGetAttribLocation(mPerVertexProgramHandle, "a_Color");
mNormalHandle = GLES20.glGetAttribLocation(mPerVertexProgramHandle, "a_Normal");
// Calculate position of the light. Rotate and then push into the distance.
Matrix.setIdentityM(mLightModelMatrix, 0);
Matrix.translateM(mLightModelMatrix, 0, 0.0f, 0.0f, -5.0f);
Matrix.rotateM(mLightModelMatrix, 0, angleInDegrees, 0.0f, 1.0f, 0.0f);
Matrix.translateM(mLightModelMatrix, 0, 0.0f, 0.0f, 2.0f);
Matrix.multiplyMV(mLightPosInWorldSpace, 0, mLightModelMatrix, 0, mLightPosInModelSpace, 0);
Matrix.multiplyMV(mLightPosInEyeSpace, 0, mViewMatrix, 0, mLightPosInWorldSpace, 0);
// Draw some cubes.
Matrix.setIdentityM(mModelMatrix, 0);
Matrix.translateM(mModelMatrix, 0, 4.0f, 0.0f, -7.0f);
Matrix.rotateM(mModelMatrix, 0, angleInDegrees, 1.0f, 0.0f, 0.0f);
drawCube();
Matrix.setIdentityM(mModelMatrix, 0);
Matrix.translateM(mModelMatrix, 0, -4.0f, 0.0f, -7.0f);
Matrix.rotateM(mModelMatrix, 0, angleInDegrees, 0.0f, 1.0f, 0.0f);
drawCube();
Matrix.setIdentityM(mModelMatrix, 0);
Matrix.translateM(mModelMatrix, 0, 0.0f, 4.0f, -7.0f);
Matrix.rotateM(mModelMatrix, 0, angleInDegrees, 0.0f, 0.0f, 1.0f);
drawCube();
Matrix.setIdentityM(mModelMatrix, 0);
Matrix.translateM(mModelMatrix, 0, 0.0f, -4.0f, -7.0f);
drawCube();
Matrix.setIdentityM(mModelMatrix, 0);
Matrix.translateM(mModelMatrix, 0, 0.0f, 0.0f, -5.0f);
Matrix.rotateM(mModelMatrix, 0, angleInDegrees, 1.0f, 1.0f, 0.0f);
drawCube();
// Draw a point to indicate the light.
GLES20.glUseProgram(mPointProgramHandle);
drawLight();
}
/**
* Draws a cube.
*/
private void drawCube()
{
// Pass in the position information
mCubePositions.position(0);
GLES20.glVertexAttribPointer(mPositionHandle, mPositionDataSize, GLES20.GL_FLOAT, false, 0, mCubePositions);
GLES20.glEnableVertexAttribArray(mPositionHandle);
// Pass in the color information
mCubeColors.position(0);
GLES20.glVertexAttribPointer(mColorHandle, mColorDataSize, GLES20.GL_FLOAT, false,
0, mCubeColors);
GLES20.glEnableVertexAttribArray(mColorHandle);
// Pass in the normal information
mCubeNormals.position(0);
GLES20.glVertexAttribPointer(mNormalHandle, mNormalDataSize, GLES20.GL_FLOAT, false,
0, mCubeNormals);
GLES20.glEnableVertexAttribArray(mNormalHandle);
// This multiplies the view matrix by the model matrix, and stores the result in the MVP matrix
// (which currently contains model * view).
Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0);
// Pass in the modelview matrix.
GLES20.glUniformMatrix4fv(mMVMatrixHandle, 1, false, mMVPMatrix, 0);
// This multiplies the modelview matrix by the projection matrix, and stores the result in the MVP matrix
// (which now contains model * view * projection).
Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);
// Pass in the combined matrix.
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);
// Pass in the light position in eye space.
GLES20.glUniform3f(mLightPosHandle, mLightPosInEyeSpace[0], mLightPosInEyeSpace[1], mLightPosInEyeSpace[2]);
// Draw the cube.
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 36);
}
/**
* Draws a point representing the position of the light.
*/
private void drawLight()
{
final int pointMVPMatrixHandle = GLES20.glGetUniformLocation(mPointProgramHandle, "u_MVPMatrix");
final int pointPositionHandle = GLES20.glGetAttribLocation(mPointProgramHandle, "a_Position");
// Pass in the position.
GLES20.glVertexAttrib3f(pointPositionHandle, mLightPosInModelSpace[0], mLightPosInModelSpace[1], mLightPosInModelSpace[2]);
// Since we are not using a buffer object, disable vertex arrays for this attribute.
GLES20.glDisableVertexAttribArray(pointPositionHandle);
// Pass in the transformation matrix.
Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mLightModelMatrix, 0);
Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);
GLES20.glUniformMatrix4fv(pointMVPMatrixHandle, 1, false, mMVPMatrix, 0);
// Draw the point.
GLES20.glDrawArrays(GLES20.GL_POINTS, 0, 1);
}
/**
* Helper function to compile a shader.
* @param shaderType The shader type.
* @param shaderSource The shader source code.
* @return An OpenGL handle to the shader.
*/
private int compileShader(final int shaderType, final String shaderSource)
{
int shaderHandle = GLES20.glCreateShader(shaderType);
if (shaderHandle != 0)
{
// Pass in the shader source.
GLES20.glShaderSource(shaderHandle, shaderSource);
// Compile the shader.
GLES20.glCompileShader(shaderHandle);
// Get the compilation status.
final int[] compileStatus = new int[1];
GLES20.glGetShaderiv(shaderHandle, GLES20.GL_COMPILE_STATUS, compileStatus, 0);
// If the compilation failed, delete the shader.
if (compileStatus[0] == 0)
{
Log.e(TAG, "Error compiling shader: " + GLES20.glGetShaderInfoLog(shaderHandle));
GLES20.glDeleteShader(shaderHandle);
shaderHandle = 0;
}
}
if (shaderHandle == 0)
{
throw new RuntimeException("Error creating shader.");
}
return shaderHandle;
}
/**
* Helper function to compile and link a program.
* @param vertexShaderHandle An OpenGL handle to an already-compiled vertex shader.
* @param fragmentShaderHandle An OpenGL handle to an already-compiled fragment shader.
* @param attributes Attributes that need to be bound to the program.
* @return An OpenGL handle to the program.
*/
private int createAndLinkProgram(final int vertexShaderHandle, final int fragmentShaderHandle, final String[] attributes)
{
int programHandle = GLES20.glCreateProgram();
if (programHandle != 0)
{
// Bind the vertex shader to the program.
GLES20.glAttachShader(programHandle, vertexShaderHandle);
// Bind the fragment shader to the program.
GLES20.glAttachShader(programHandle, fragmentShaderHandle);
// Bind attributes
if (attributes != null)
{
final int size = attributes.length;
for (int i = 0; i < size; i++)
{
GLES20.glBindAttribLocation(programHandle, i, attributes[i]);
}
}
// Link the two shaders together into a program.
GLES20.glLinkProgram(programHandle);
// Get the link status.
final int[] linkStatus = new int[1];
GLES20.glGetProgramiv(programHandle, GLES20.GL_LINK_STATUS, linkStatus, 0);
// If the link failed, delete the program.
if (linkStatus[0] == 0)
{
Log.e(TAG, "Error compiling program: " + GLES20.glGetProgramInfoLog(programHandle));
GLES20.glDeleteProgram(programHandle);
programHandle = 0;
}
}
if (programHandle == 0)
{
throw new RuntimeException("Error creating program.");
}
return programHandle;
}
}
