嗨，我尝试使用 OpenGL ES 中的前向渲染技术创建贴花着色器。所以我需要一个对象来渲染（大多数时候是一个盒子）。然后我有贴花纹理和场景深度纹理。agk_XXXX 制服是当前的相机矩阵，希望能自我解释。我不确定是否需要以某种方式再次将位置取消投影到模型空间中，以及我将如何做到这一点。我不确定我的方法是否正确？！目前它以某种方式工作，但只是好像贴花对象是相机......这是我的顶点着色器：
attribute vec3 position;
attribute vec3 normal;
attribute vec2 uv;
varying vec2 uvVarying;
varying highp vec3 posVarying;
varying vec3 normalVarying;
varying highp vec4 clipSpace;
uniform vec4 uvBounds0;
uniform mat4 agk_World;
uniform mat4 agk_View;
uniform mat4 agk_Proj;
uniform mat4 agk_ViewProj;
uniform mat3 agk_WorldNormal;
uniform mat4 agk_WorldViewProj;
void main()
{
uvVarying = uv * uvBounds0.xy + uvBounds0.zw;
vec4 pos = agk_World * vec4(position,1);
posVarying = pos.xyz;
clipSpace = agk_ViewProj * pos;
gl_Position = agk_WorldViewProj * vec4(position,1);
vec3 norm = agk_WorldNormal * normal;
normalVarying = norm;
}
这是我的片段着色器：
uniform sampler2D texture0; //decal texture
uniform highp sampler2D texture1; //scene depth
varying mediump vec2 uvVarying;
varying highp vec3 posVarying;
varying mediump vec3 normalVarying;
varying highp vec4 clipSpace;
uniform mediump vec2 cameraRange;
uniform mediump vec2 agk_resolution;
uniform lowp float agk_invert;
uniform mediump vec3 agk_CameraPos;
uniform mediump mat4 agk_World;
uniform mediump mat4 agk_View;
uniform mediump mat4 agk_Proj;
mat4 inverse(mat4 m);
void main()
{
highp vec2 ndc = (clipSpace.xy/clipSpace.w) * 0.5 + 0.5;
ndc = vec2(ndc.x, mix(ndc.y,1.0-ndc.y, agk_invert * 0.5 + 0.5));
highp float worldDepth = texture2D(texture1, ndc ).r;
vec2 deproject = vec2(agk_Proj[1][1],agk_Proj[2][2]);
vec4 position = vec4(clipSpace.xy * worldDepth / (deproject * clipSpace.w), -worldDepth,1.0);
position *= inverse(agk_World * agk_View);
vec2 textureCoordinate = position.xz + 0.5;
gl_FragColor = texture2D(texture0,textureCoordinate);
}
mat4 inverse(mat4 m)
{
float
a00 = m[0][0], a01 = m[0][1], a02 = m[0][2], a03 = m[0][3],
a10 = m[1][0], a11 = m[1][1], a12 = m[1][2], a13 = m[1][3],
a20 = m[2][0], a21 = m[2][1], a22 = m[2][2], a23 = m[2][3],
a30 = m[3][0], a31 = m[3][1], a32 = m[3][2], a33 = m[3][3],
b00 = a00 * a11 - a01 * a10,
b01 = a00 * a12 - a02 * a10,
b02 = a00 * a13 - a03 * a10,
b03 = a01 * a12 - a02 * a11,
b04 = a01 * a13 - a03 * a11,
b05 = a02 * a13 - a03 * a12,
b06 = a20 * a31 - a21 * a30,
b07 = a20 * a32 - a22 * a30,
b08 = a20 * a33 - a23 * a30,
b09 = a21 * a32 - a22 * a31,
b10 = a21 * a33 - a23 * a31,
b11 = a22 * a33 - a23 * a32,
det = b00 * b11 - b01 * b10 + b02 * b09 + b03 * b08 - b04 * b07 + b05 * b06;
return mat4(
a11 * b11 - a12 * b10 + a13 * b09,
a02 * b10 - a01 * b11 - a03 * b09,
a31 * b05 - a32 * b04 + a33 * b03,
a22 * b04 - a21 * b05 - a23 * b03,
a12 * b08 - a10 * b11 - a13 * b07,
a00 * b11 - a02 * b08 + a03 * b07,
a32 * b02 - a30 * b05 - a33 * b01,
a20 * b05 - a22 * b02 + a23 * b01,
a10 * b10 - a11 * b08 + a13 * b06,
a01 * b08 - a00 * b10 - a03 * b06,
a30 * b04 - a31 * b02 + a33 * b00,
a21 * b02 - a20 * b04 - a23 * b00,
a11 * b07 - a10 * b09 - a12 * b06,
a00 * b09 - a01 * b07 + a02 * b06,
a31 * b01 - a30 * b03 - a32 * b00,
a20 * b03 - a21 * b01 + a22 * b00) / det;
}