c++ - Opengl ES 2.0-glDrawElements(GL_TRIANGLES)出现颜色不透明的问题

Question

我创建了用于在opengl es 2.0中绘制正方形的简单c++类。它在具有特定颜色和不透明度的特定位置放置正方形。一切都很好，除了不透明度。我使用功能“setColor”设置颜色和不透明度。我期望0.0f完全透明，而1.0完全可见。看起来，对于黑色它可以工作，但是白色仍然是完全可见的，与我设置的不透明度无关紧要。对于其他颜色，不透明度也很奇怪。

一开始我设定

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);

我的课 :

GLSquare::GLSquare() {
    vecs = new std::vector<GLfloat>();
    indices = new std::vector<GLshort>();
    colors = new std::vector<GLfloat>();
    indicesCount = 6;

    for (int i = 0; i < 12; i++) {
        vecs->push_back(0.0f);
    }

    for (int i=0; i<16; i+=4) {
        colors->push_back(0.0f);
        colors->push_back(0.0f);
        colors->push_back(0.0f);
        colors->push_back(1.0f);
    }

    GLshort ind[] = { 0, 1, 2, 0, 2, 3 };
    for (int i = 0; i < indicesCount; i++) {
        indices->push_back(ind[i]);
    }
}

GLSquare::~GLSquare() {
    delete vecs;
    delete colors;
    delete indices;
}

void GLSquare::draw(Matrix *matrix) {
    glUseProgram(program->id);

    glEnableVertexAttribArray(program->positionHandle);

    glVertexAttribPointer(program->positionHandle, 3, GL_FLOAT, false, 12, &vecs->front());

    glEnableVertexAttribArray(program->colorHandle);

    // Prepare the background coordinate data
    glVertexAttribPointer(program->colorHandle, 4, GL_FLOAT, false, 0, &colors->front());

    glUniformMatrix4fv(program->matrixHandle, 1, false, matrix->projectionAndView);
    glDrawElements(GL_TRIANGLES, indicesCount, GL_UNSIGNED_SHORT, &indices->front());

    glDisableVertexAttribArray(program->positionHandle);
    glDisableVertexAttribArray(program->colorHandle);
}

void GLSquare::set(float left, float top, float width, float height) {
    position[0] = left;
    position[1] = top;
    size[0] = width;
    size[1] = height;

    vecs->at(0) = left;
    vecs->at(1) = top;

    vecs->at(3) = left;
    vecs->at(4) = top + height;

    vecs->at(6) = left + width;
    vecs->at(7) = top + height;

    vecs->at(9) = left + width;
    vecs->at(10) = top;
}

void GLSquare::setColor(Color color, GLfloat opacity) {
    for (int i=0; i<16; i+=4) {
        colors->at(i) = color.r;
        colors->at(i + 1) = color.g;
        colors->at(i + 2) = color.b;
        colors->at(i + 3) = opacity;
    }
}

我的片段着色器很简单:

precision mediump float; 

varying vec4 v_Color;

void main() 
{ 
    gl_FragColor = v_Color;
}

我的顶点着色器:

uniform   mat4 uMVPMatrix;

attribute vec4 vPosition;
attribute vec4 a_Color;

varying vec4 v_Color;

void main() 
{ 
   gl_Position = uMVPMatrix * vPosition;
   v_Color = a_Color;
}

从着色器获取colorHandle:

program->colorHandle = glGetAttribLocation(programID, "a_Color");

这是它的外观:

square-> setColor(Color(1.0f，1.0f，1.0f)，0.1f);

左上角的白色矩形



这是黑色，不透明度0.1

Answer 1

我发现了问题。代码正常工作，其他第3方库将覆盖glBlendFunc。修复它解决了这个问题