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GLSL Textures


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#1 The Topher   Members   -  Reputation: 161

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Posted 20 June 2006 - 06:50 PM

Well, I wrote a nice little terrain texturing shader in HLSL (it's not great, but give me a break, it's my first attempt at one :P). Unfortunately, I now need it in HLSL, I've tried tweaking it to be Cg compatible and compiling with the GLSL profiles. That failed miserably. So I went and ported it manually (which wasn't actually too bad). Now the problem is, the textures don't show up at all. The original HLSL code is (ignore the highlighting):
//---------------------------------
// Projection Matrices and stuff...
//---------------------------------
float4x4 world : WorldViewProjection;

//---------------------------------
// User definable parameter
//---------------------------------
float HighAltDef <
	string UIName = "High Altitude";
	string UIWidget = "slider";
	float UImin = 0;
	float UImax = 50;
	float UIstep = 0.1;
> = 25;

float HighFringeSize <
	string UIName = "High Fringe Size";
	string UIWidget = "slider";
	float UImin = 0;
	float UImax = 25;
	float UIstep = 0.1;
> = .5;

float LowFringeSize <
	string UIName = "Low Fringe Size";
	string UIWidget = "slider";
	float UImin = 0;
	float UImax = 25;
	float UIstep = 0.1;
> = .5;

float Tiles <
	string UIName = "Tile";
	string UIWidget = "slider";
	float UImin = 0;
	float UImax = 32;
	float UIstep = 0.1;
> = 1;

float3 LightPos : POSITION <
	string UIName = "Light Position";
	string object = "spotlight";
> = {-150, 0, 50};

float3 LightColor <
	string UIName = "Light Color";
	string UIWidget = "color";
> = {1, 1, 1};

//---------------------------------
// Textures
//---------------------------------
texture highAlt;
texture lowAlt;
texture fringeTex;

//---------------------------------
// Texture Samplers
//---------------------------------
sampler2D high = sampler_state {
	texture = (highAlt);
	mipfilter = linear;
	minfilter = linear;
	magfilter = linear;
};

sampler2D low = sampler_state {
	texture = (lowAlt);
	mipfilter = linear;
	minfilter = linear;
	magfilter = linear;
};

sampler2D fringe = sampler_state {
	texture = (fringeTex);
	mipfilter = linear;
	minfilter = linear;
	magfilter = linear;
};

//---------------------------------
// Application->Vertex Pipeline
//---------------------------------
struct a2v {
	float4 position : POSITION0;
	float3 normal : NORMAL;
	float2 uv : TEXCOORD0;
};

//---------------------------------
// Vertex Pipe to Pixel Pipe
//---------------------------------
struct v2p {
	float4 position : POSITION;
	float4 pos : TEXCOORD0;
	float3 normal : TEXCOORD1;
	float2 uv : TEXCOORD2;
	float height : TEXCOORD3;
};

//---------------------------------
// Pixel Pipe to Frame
//---------------------------------
struct p2f {
	float4 color : COLOR;
};

//---------------------------------
// Vertex Shader
//---------------------------------
void vs(in a2v IN, out v2p OUT) {
	// Output Position
	OUT.position = mul(IN.position, world);
	OUT.pos = OUT.position;
	
	// Normal transfer
	OUT.normal = IN.normal;
	
	// Output Texture Coordinates
	OUT.uv = IN.uv;
	
	// Store vertex height
	OUT.height = IN.position.y;
}

//---------------------------------
// Pixel Shader
//---------------------------------
void ps(in v2p IN, out p2f OUT) {
	if(IN.height > HighAltDef) {
		float fringepoint = clamp((IN.height - HighAltDef) / HighFringeSize, 0, 1);
		OUT.color = tex2D(high, IN.uv * Tiles) * fringepoint + tex2D(fringe, IN.uv * Tiles) * (1 - fringepoint);
	} else {
		float fringepoint = clamp((HighAltDef - IN.height) / LowFringeSize, 0, 1);
		OUT.color = tex2D(low, IN.uv * Tiles) * fringepoint + tex2D(fringe, IN.uv * Tiles) * (1 - fringepoint);
	}
	
	// Per-Pixel lighting
	float3 pworld = mul(IN.pos, world).xyz;
	float3 normal = mul(IN.normal, world).xyz;
	float3 light = normalize(LightPos - pworld);
	float intense = clamp(dot(normal, light), 0, 1);
	float4 color = float4(LightColor * intense, 1);
	color.rgb += 0.5;
	
	OUT.color *= color;
}

//---------------------------------
// Techniques
//---------------------------------
technique Textured {
	pass p0 {
		vertexshader = compile vs_1_1 vs();
		pixelshader = compile ps_2_0 ps();
	}
}
The GLSL version I've created is as follows: Vertex
varying float height;
varying vec3 normal;
varying vec4 pos;

void main() {
	height = gl_Vertex.y;
	normal = gl_Normal;
	pos = gl_Vertex;
	gl_Position = ftransform();
}
Fragment
uniform float HighAltDef;
uniform float Tiles;
uniform float HighFringeSize;
uniform float LowFringeSize;
uniform vec3 LightPos;
uniform sampler2D high;
uniform sampler2D low;
uniform sampler2D fringe;
uniform vec3 LightColor;

varying float height;
varying vec3 normal;
varying vec4 pos;

void main() {
	if(height > HighAltDef) {
		float fringep = clamp((height - HighAltDef) / HighFringeSize, 0.0, 1.0);
		gl_FragColor = texture2D(high, gl_TexCoord[0].st * Tiles) * fringep + texture2D(fringe, gl_TexCoord[0].st * Tiles) * (1.0 - fringep);
	} else {
		float fringep = clamp((HighAltDef - height) / LowFringeSize, 0.0, 1.0);
		gl_FragColor = texture2D(low, gl_TexCoord[0].st * Tiles) * fringep + texture2D(fringe, gl_TexCoord[0].st * Tiles) * (1.0 - fringep);
	}
	
	vec4 WorldPos = pos * gl_ModelViewProjectionMatrix;
	vec3 light = normalize(LightPos - WorldPos.xyz);
	float intense = clamp(dot(normal, light), 0.0, 1.0);
	vec4 color = vec4(LightColor * intense, 1);
	color.rgb += 0.5;
	
	gl_FragColor *= color;
}
I assume I must be doing something wrong in the Fragment shader because I end up with a shaded red block of land. I can't see anything that could be wrong, but this is only the second day I've done anything with shader writing. Thanks.

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#2 nts   Members   -  Reputation: 968

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Posted 20 June 2006 - 07:04 PM

Add this line to your vertex shader otherwise the tex coords are undefined.

gl_TexCoord[0] = gl_MultiTexCoord0;




#3 The Topher   Members   -  Reputation: 161

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Posted 20 June 2006 - 07:11 PM

Hey it worked (after restarting RenderMonkey). Thanks.




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