Android glOrtho OpenGL es 2.0变体如何修复空白屏幕?
我尝试为Android重新制作一个OpenGL ES 2.0示例 到Android NDK OpenGL ES 2.0示例。Android glOrtho OpenGL es 2.0变体如何修复空白屏幕?,android,c,opengl-es,opengl-es-2.0,Android,C,Opengl Es,Opengl Es 2.0,我尝试为Android重新制作一个OpenGL ES 2.0示例 到Android NDK OpenGL ES 2.0示例。 除了做正交投影/透视投影外,我其他都成功了 所以我画了一个三角形 typedef matrix float matrix[16]; matrix MVP_MATRIX; /* MODEL*VIEW*PROJECTION MATRIX */ matrix PROJECTION_MATRIX; matrix MODEL_MATRIX; matrix VIEW_MATRIX;
除了做正交投影/透视投影外,我其他都成功了 所以我画了一个三角形
typedef matrix float matrix[16];
matrix MVP_MATRIX; /* MODEL*VIEW*PROJECTION MATRIX */
matrix PROJECTION_MATRIX;
matrix MODEL_MATRIX;
matrix VIEW_MATRIX;
s_shader shader; /* just struct for holding shader program data (attribytes,uniforms, fragment shader, vertex shader etc)*/
GLfloat triangle_vertices[] =
{
0.0f, 0.5f, 0.0f,
-0.5f, -0.5f, 0.0f,
0.5f, -0.5f, 0.0f
};
onInit(float screen_width, float screen_height)
{
/*shader load*/
matrix MV_MATRIX;
identity_matrix(MODEL_MATRIX); //any transitions/rotations works fine
identity_matrix(VIEW_MATRIX);
multiply_matrix(VIEW_MATRIX, MODEL_MATRIX, MV_MATRIX);
glViewport(0, 0, screen_width, screen_height);
ortho_matrix(0.0,screen_width,0.0,screen_height,1.0,10.0, PROJECTION_MATRIX);
multiply_matrix(MV_MATRIX, PROJECTION_MATRIX , MVP_MATRIX);
}
onDraw()
{
glClear(GL_COLOR_BUFFER_BIT);
glUseProgram(shader.program /* where i hold a compiled shader program */ );
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, triangle_vertices);
glUniformMatrix4fv(shader.uniforms[0]/*"umWorld" uniform location*/, 1, GL_FALSE, (const GLfloat*) MVP_MATRIX/*Well get blank screen, if change to MV_MATRIX everything is fine, so projection matrix is problem*/);
glEnableVertexAttribArray(shader.atributes[0]/*"vPosition" attribute location*/);
glDrawArrays(GL_TRIANGLES, 0, 3);
}
void ortho_matrix(float left, float right, float bottom, float top, float near,
float far, matrix result)
{
result[0] = 2.0 / (right - left);
result[1] = 0.0;
result[2] = 0.0;
result[3] = 0.0;
//Second Column
result[4] = 0.0;
result[5] = 2.0 / (top - bottom);
result[6] = 0.0;
result[7] = 0.0;
//Third Column
result[8] = 0.0;
result[9] = 0.0;
result[10] = -2.0 / (far - near);
result[11] = 0.0;
//Fourth Column
result[12] = -(right + left) / (right - left);
result[13] = -(top + bottom) / (top - bottom);
result[14] = -(far + near) / (far - near);
result[15] = 1;
}
顶点着色器
attribute vec4 vPosition;
uniform mat4 umWorld;
void main()
{
gl_Position = umWorld * vPosition;
}
片段着色器
precision lowp float;
void main()
{
gl_FragColor = vec4(1.0,0.0,1.0,1.0);
}
另外,我想我把错误的东西传给了正交矩阵,因为opengl es有(-1,-1,-1)-(1,1,1)坐标系。首先,你的三角形似乎被近平面剪裁了。默认视图位于-z轴下方的0,0,0处,三角形位于z轴上的位置0处,近平面为1 沿负z轴向下移动三角形(对于所有顶点,请尝试-5),或者向后移动近平面(如果需要,也可以将其设置为负,请尝试-10到10) 这些信息还远远不够继续下去。你在画什么?你在哪里画?浮动纵横比=(浮动)屏幕宽度/屏幕高度;正交矩阵(-aspect_ratio,aspect_ratio,-1.0,1.0,-1.0,1.0,PROJECTION_matrix);-很有魅力