我正在尝试制作一个使用 OpenGL 显示文本的应用程序。当我尝试使用Matrix.translateM
将指定对象移动到特定位置时出现意外行为。所有其他转换矩阵都按我的预期工作。
这是我打电话时得到的Matrix.translateM(model_matrix, 0, -1.0f, 0, 0)
:
这是没有翻译的图像:
这是我的渲染器代码。
@Override
public void onSurfaceCreated(GL10 unused, EGLConfig config) {
GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
GLES20.glDisable(GLES20.GL_DEPTH_TEST);
GLES20.glEnable(GLES20.GL_BLEND);
GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA);
// create programs
simple_texture = new SimpleTexture();
// create shapes
square = new Square();
// create debug text handlers
text_fps = new Text(this.font, this.text_scale);
text_fps.setSize(50);
text_fps.setText("Test\nLonger line");
// set camera position
final float eyeX = 0.0f;
final float eyeY = 0.0f;
final float eyeZ = -3.0f;
final float lookX = 0.0f;
final float lookY = 0.0f;
final float lookZ = 0.0f;
final float upX = 0.0f;
final float upY = 1.0f;
final float upZ = 0.0f;
Matrix.setLookAtM(view_matrix, 0, eyeX, eyeY, eyeZ, lookX, lookY, lookZ, upX, upY, upZ);
}
@Override
public void onSurfaceChanged(GL10 unused, int width, int height) {
GLES20.glViewport(0, 0, width, height);
// set projection matrix
float ratio = (float) width / height;
Matrix.orthoM(projection_matrix, 0, -ratio, ratio, -1, 1, 3, 7);
setScreenRatio(ratio);
setScreenHeight(height);
}
@Override
public void onDrawFrame(GL10 unused) {
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
// calculate projection and view transformation
Matrix.multiplyMM(vp_matrix, 0, projection_matrix, 0, view_matrix, 0);
// if we are connected to debugger draw statistics
drawStatistics(vp_matrix);
}
这是我draw
的文本代码。
// use predefined program
GLES20.glUseProgram(program);
// get attribute positions
attr_matrix = GLES20.glGetUniformLocation(program, "u_Matrix");
attr_position = GLES20.glGetAttribLocation(program, "a_Position");
attr_texture_position = GLES20.glGetAttribLocation(program, "a_TexturePosition");
attr_texture = GLES20.glGetUniformLocation(program, "u_Texture");
// set program parameters
GLES20.glEnableVertexAttribArray(attr_position);
GLES20.glVertexAttribPointer(attr_position, 2, GLES20.GL_FLOAT, false, 2 * 4, square_buffer);
// set texture parameters
GLES20.glEnableVertexAttribArray(attr_texture_position);
GLES20.glVertexAttribPointer(attr_texture_position, 2, GLES20.GL_FLOAT, false, 2 * 4, texture_buffer);
// set matrix
float[] result = new float[16];
float ratio = (float) texture_height / texture_width;
float screen_scale = (float) texture_height / PageRenderer.getScreenHeight();
Matrix.setIdentityM(model_matrix, 0);
Matrix.translateM(model_matrix, 0, -1, 0, 0);
Matrix.scaleM(model_matrix, 0, screen_scale, screen_scale * ratio, screen_scale);
Matrix.setIdentityM(result, 0);
Matrix.multiplyMM(result, 0, matrix, 0, model_matrix, 0);
GLES20.glUniformMatrix4fv(attr_matrix, 1, false, result, 0);
// assign texture
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, index);
GLES20.glUniform1i(attr_texture, 0);
// perform drawing
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
// disable vertex array
GLES20.glDisableVertexAttribArray(attr_position);
GLES20.glDisableVertexAttribArray(attr_texture_position);
着色器:
int vertex_shader = PageRenderer.loadShader(
GLES20.GL_VERTEX_SHADER,
"uniform mat4 u_Matrix;" +
"attribute vec4 a_Position;" +
"attribute vec2 a_TexturePosition;" +
"varying vec2 v_TexturePosition;" +
"void main() {" +
" gl_Position = a_Position * u_Matrix;" +
" v_TexturePosition = a_TexturePosition;" +
"}"
);
int fragment_shader = PageRenderer.loadShader(
GLES20.GL_FRAGMENT_SHADER,
"precision mediump float;" +
"varying vec2 v_TexturePosition;" +
"uniform sampler2D u_Texture;" +
"void main() {" +
" gl_FragColor = texture2D(u_Texture, v_TexturePosition);" +
"}"
);
缩放和旋转按预期工作,但我不知道为什么 translate 没有。请注意,我直到最近才使用 OpenGL。
我期待translateM
将文本向左移动,而不是“旋转”它。