我正在尝试让 GLSL 片段着色器根据纹理坐标将传入片段扭曲为 。
这让我相信我的 GLSL 代码有问题,即使它在 C++ 中镜像并且工作完美。
有什么我不知道的 GLSL 数学知识可能会导致这种情况吗?
C++代码
const unsigned int RED = 0xFFFF0000;
const unsigned int BLUE = 0xFF0000FF;
const float X_MAX = 429.0f/448.0f;
const float Y_MAX = 320.0f/336.0f;
const float X_CORNER = 410.0f/448.0f;
const float Y_CORNER = 306.0f/336.0f;
const float X_COEF = (X_MAX-X_CORNER) / (Y_CORNER * Y_CORNER);
const float Y_COEF = (Y_MAX-Y_CORNER) / (X_CORNER * X_CORNER);
float FUNCX(float y)
{
return X_MAX-X_COEF*y*y;
}
float FUNCY(float x)
{
return Y_MAX-Y_COEF*x*x;
}
unsigned int get(glm::vec2 intex)
{
intex *= 2.0; // Transform the texture rectangle from 0..1
intex.x -= 1.0; // to
intex.y -= 1.0; // -1 .. 1
glm::vec2 d = glm::vec2(0.0,0.0);
d.x = FUNCX(intex.y); // get the curve amount for X values based on Y input
d.y = FUNCY(intex.x); // get the curve amount for Y values based on X input
if (abs(intex.x/d.x) > 1.0) // if the X value is outside of the curve
return RED; // draw RED for debugging
if (abs(intex.y/d.y) > 1.0) // if the Y value is outside of the curve
return BLUE; // draw BLUE for debugging
glm::vec2 outtex = glm::vec2(0.0f,0.0f);
outtex.x = 1.0 + intex.x/d.x; // Now the -1 .. 1 values get shifted back
outtex.y = 1.0 + intex.y/d.y; // to
outtex /= 2.0; // 0 .. 1
return texture.get(512*outtex.x,512*outtex.y);
}
GLSL 片段着色器
const vec4 RED = vec4(1.0,0.0,0.0,1.0);
const vec4 BLUE = vec4(0.0,0.0,1.0,1.0);
const float X_MAX = 429.0/448.0;
const float Y_MAX = 320.0/336.0;
const float X_CORNER = 410.0/448.0;
const float Y_CORNER = 306.0/336.0;
const float X_COEF = (X_MAX-X_CORNER) / (Y_CORNER * Y_CORNER);
const float Y_COEF = (Y_MAX-Y_CORNER) / (X_CORNER * X_CORNER);
float FUNCX(float y)
{
return X_MAX-X_COEF*y*y;
}
float FUNCY(float x)
{
return Y_MAX-Y_COEF*x*x;
}
vec4 get(vec2 intex)
{
intex *= 2.0; // Transform the texture rectangle from 0..1
intex.x -= 1.0; // to
intex.y -= 1.0; // -1 .. 1
vec2 d = vec2(0.0,0.0);
d.x = FUNCX(intex.y); // get the curve amount for X values based on Y input
d.y = FUNCY(intex.x); // get the curve amount for Y values based on X input
if (abs(intex.x/d.x) > 1.0) // if the X value is outside of the curve
return RED; // draw RED for debugging
if (abs(intex.y/d.y) > 1.0) // if the Y value is outside of the curve
return BLUE; // draw BLUE for debugging
vec2 outtex = vec2(0.0,0.0);
outtex.x = 1.0 + intex.x/d.x; // Now the -1 .. 1 values get shifted back
outtex.y = 1.0 + intex.y/d.y; // to
outtex /= 2.0; // 0 .. 1
return texture2D(texture,outtex);
}
注意:《超级马里奥世界》图像仅用于测试目的。 注2:C++代码中的512个值是所使用纹理的大小。
代码不一样。在 C++ 代码中:
if (abs(intex.y/d.y) > 1.0) // if the Y value is outside of the curve
return BLUE; // draw BLUE for debugging
在 GLSL 代码中:
if (abs(intex.y/d.x) > 1.0) // if the Y value is outside of the curve
return BLUE; // draw BLUE for debugging
C++ 版本除以
d.y
,GLSL 版本除以 d.x
。