我已经编写了一个基本的 2d 像素着色器,但我似乎无法让它工作。如果我在激活效果的情况下进行绘制,那么屏幕上不会出现任何内容。但是如果我禁用它,那么纹理会按预期绘制到屏幕上。
我的目标是能够在屏幕上绘制任意纹理,然后让这个像素着色器“雕刻”出圆形像素块,用于范围等的覆盖系统。
这是我的像素着色器代码:
sampler TextureSampler : register(s0);
//A list of positions for circles. They are specified in texture space rather than screen space.
float2 PositionData[64];
//A matching list of radiuses. These are specified in pixels, though.
float Radii[64];
//how much of the array is filled with data.
int DataSize;
//the size of the texture being drawn.
float2 TextureSize;
float4 RenderSolidCircles(float2 texCoord : TEXCOORD0) : COLOR
{
float opacityAcc = 1;
float2 screenSpaceTexCoord = texCoord * TextureSize;
for (int i = 0; i < DataSize; i++)
{
float2 properPosCoordinate = PositionData[i] * TextureSize;
float dist = length(screenSpaceTexCoord - properPosCoordinate) - Radii[i];
if (dist < 0)
{
opacityAcc -= min(abs(dist), 1);
}
}
opacityAcc = max(0, opacityAcc);
float4 outPix = tex2D(TextureSampler, texCoord);
outPix.a *= opacityAcc;
return outPix;
}
technique SolidCircles
{
pass P0
{
PixelShader = compile ps_3_0 RenderSolidCircles();
}
}
float4 PassThrough(float2 texCoord : TEXCOORD0) : COLOR
{
return tex2D(TextureSampler, texCoord);
}
technique PassThrough
{
pass P0
{
PixelShader = compile ps_3_0 PassThrough();
}
}
这是 SolidCircles 技术的 ASM 版本:
//
// Generated by Microsoft (R) D3DX9 Shader Compiler 9.15.779.0000
//
// Parameters:
//
// int DataSize;
// float2 PositionData[64];
// float Radii[64];
// sampler2D TextureSampler;
// float2 TextureSize;
//
//
// Registers:
//
// Name Reg Size
// -------------- ----- ----
// PositionData c0 64
// Radii c64 64
// DataSize c128 1
// TextureSize c129 1
// TextureSampler s0 1
//
//
// Default values:
//snipped comments here
ps_3_0
def c130, 1, 0, -1, 2
def c131, 3, 4, 5, 6
def c132, 7, 8, 9, 10
def c133, 11, 12, 13, 14
def c134, 15, 16, 17, 18
def c135, 19, 20, 21, 22
def c136, 23, 24, 25, 26
def c137, 27, 28, 29, 30
def c138, 31, 32, 33, 34
def c139, 35, 36, 37, 38
def c140, 39, 40, 41, 42
def c141, 43, 44, 45, 46
def c142, 47, 48, 49, 50
def c143, 51, 52, 53, 54
def c144, 55, 56, 57, 58
def c145, 59, 60, 61, 62
def c146, 63, 0, 0, 0
dcl_texcoord v0.xy // texCoord<0,1>
dcl_2d s0
#line 22 "C:\Users\RCIX\Documents\Visual Studio 2008\Projects\2DFXFilesTest\2DFXFilesTest\Content\OverlayFx.fx"
mov r0.w, c130.x // opacityAcc<0>
mul r2.xy, v0, c129 // screenSpaceTexCoord<0,1>
mov r5.w, -c128.x
add r0.z, r5.w, c130.y
cmp r12.w, r0.z, c130.y, c130.x
mul r11.w, r12.w, c130.x
if_ne r11.w, -r11.w
mov r13.xy, c129 // ::TextureSize<0,1>
mul r12.xy, r13, c0 // properPosCoordinate<0,1>
mov r12.xy, -r12
add r11.xy, r2, r12
mul r16.xy, r11, r11
add r11.z, r16.x, r16.y
rsq r10.w, r11.z
rcp r8.w, r10.w
mov r9.w, -c64.x
add r4.w, r8.w, r9.w // dist<0>
add r7.w, r4.w, c130.y
cmp r6.w, r7.w, c130.y, c130.x
mov r3.w, -r4.w
mov r5.z, -r3.w
add r1.w, r4.w, r5.z
cmp r15.w, r1.w, r4.w, r3.w
add r14.w, r15.w, c130.z
cmp r2.w, r14.w, c130.x, r15.w
mov r2.w, -r2.w
add r13.w, r2.w, c130.x // opacityAcc<0>
mov r6.w, -r6.w
cmp r0.w, r6.w, r0.w, r13.w // opacityAcc<0>
#line 24
endif
//snipped 63 blocks of unrolled loop code
#line 33
mov r1.w, -r0.w
add r15.w, r1.w, c130.y
cmp r14.w, r15.w, c130.y, r0.w // opacityAcc<0>
texld r0, v0, s0 // outPix<0,1,2,3>
mul r2.x, r14.w, r0.w // outPix<3>
mov oC0.xyz, r0 // ::RenderSolidCircles<0,1,2>
mov oC0.w, r2.x // ::RenderSolidCircles<3>
// approximately 1866 instruction slots used (1 texture, 1865 arithmetic)
这是我的 Game 类中 Draw 函数的相关部分:
GraphicsDevice.Clear(Color.CornflowerBlue);
overlayEffect.Parameters["PositionData"].SetValue(Positions.ToArray());
overlayEffect.Parameters["Radii"].SetValue(Radii.ToArray());
overlayEffect.Parameters["DataSize"].SetValue(64);
overlayEffect.Parameters["TextureSize"].SetValue(new Vector2(500));
spriteBatch.Begin(SpriteBlendMode.AlphaBlend,
SpriteSortMode.Immediate,
SaveStateMode.None);
overlayEffect.Begin();
overlayEffect.CurrentTechnique.Passes[0].Begin();
spriteBatch.Draw(pixTex, new Rectangle(0, 0, 500, 500), Color.White);
spriteBatch.End();
overlayEffect.CurrentTechnique.Passes[0].End();
overlayEffect.End();
base.Draw(gameTime);
最后,这是我构建位置和半径列表的函数:
private void RebuildPositionsList()
{
spriteBatch = new SpriteBatch(GraphicsDevice);
Positions = new List<Vector2>();
Radii = new List<float>();
for (int i = 0; i < 64; i++)
{
Positions.Add(
new Vector2(
(float)r.NextDouble(),
(float)r.NextDouble())
);
Radii.Add(((float)r.NextDouble() * 100) + 40);
}
}
构成我纹理的线条:
pixTex = new Texture2D(GraphicsDevice, 1, 1);
pixTex.SetData<Color>(new Color[] { new Color(0f, 0f, 0f, 1f) });
Positions
和Radii
分别是向量列表和浮点数,大小为 64。 pixTex 是一个 1 像素纯黑色纹理。
为什么着色器不起作用?