关于android：OpenGL ES 2.0/3.0 中的折射。大像素纹理

Refraction in OpenGL ES 2.0/3.0. Large pixels texture

尝试在 OpenGL ES 2.0/3.0 中实现折射。使用了以下着色器：

顶点着色器：

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#version 300 es
precision lowp float;
uniform mat4 u_mvMatrix;

in vec4 a_position;
in vec3 a_normal;
…
out mediump vec2 v_refractCoord;

const mediump float eta = 0.95;

void main() {
vec4 eyePositionModel = u_mvMatrix * a_position;

// eye direction in model space
mediump vec3 eyeDirectModel = normalize(a_position.xyz – eyePositionModel.xyz);

// calculate refraction direction in model space
mediump vec3 refractDirect = refract(eyeDirectModel, a_normal, eta);

// project refraction
refractDirect = (u_mvpMatrix * vec4(refractDirect, 0.0)).xyw;

// map refraction direction to 2d coordinates
v_refractCoord = 0.5 * (refractDirect.xy / refractDirect.z) + 0.5;
…
}

片段着色器：

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…
in mediump vec2 v_refractCoord;
uniform samplerCube s_texture; // skybox

void main() {
outColor = texture(s_texture, vec3(v_refractCoord, 1.0));
}

纹理加载方法：

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@JvmStatic
fun createTextureCubemap(context: Context, rowID: Int) {
val input = context.resources.openRawResource(rowID)
val bitmap = BitmapFactory.decodeStream(input)

val textureId = IntArray(1)
glGenTextures(1, textureId, 0)
glBindTexture(GL_TEXTURE_CUBE_MAP, textureId[0])

GLUtils.texImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X, 0, bitmap, 0)
GLUtils.texImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_X, 0, bitmap, 0)
GLUtils.texImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Y, 0, bitmap, 0)
GLUtils.texImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, 0, bitmap, 0)
GLUtils.texImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 0, bitmap, 0)
GLUtils.texImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, 0, bitmap, 0)

glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
return textureId[0]
}