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Fixing shaders for lighting terrain.


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#1 Syerjchep   Members   -  Reputation: 180

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Posted 07 September 2013 - 01:22 PM

I've been making a new opengl program which uses shaders and the shaders support up to 8 dynamic lights.
This worked fine when I was just loading models and testing them.
But now that I've added some terrain the light acts very odd with it.

farAwayHillside.png
The further away from the light I go, the more you can actually see it.

closeUpHillside.png
If you get within a reasonable distance, however, the lights vanish.

litPlants.png
This bug does not seem to effect the models very much.

Here is my fragment shader:

#version 330 core

// Interpolated values from the vertex shaders
in vec2 UV;
in vec3 Position_worldspace;
in vec3 Normal_cameraspace;
in vec3 EyeDirection_cameraspace;
in vec3 ambientColor;
in vec3 diffuseColor;
in vec3 specularColor;

in vec3 Light0Direction_cameraspace;
in vec3 Light1Direction_cameraspace;
in vec3 Light2Direction_cameraspace;
in vec3 Light3Direction_cameraspace;
in vec3 Light4Direction_cameraspace;
in vec3 Light5Direction_cameraspace;
in vec3 Light6Direction_cameraspace;
in vec3 Light7Direction_cameraspace;

// Ouput data
out vec3 color;

// Values that stay constant for the whole mesh.
uniform sampler2D myTextureSampler;
uniform mat4 MV;
uniform int textured;
uniform int terrain;
uniform vec3 worldAmbient;

uniform vec3 Light0_Position;
uniform vec3 Light1_Position;
uniform vec3 Light2_Position;
uniform vec3 Light3_Position;
uniform vec3 Light4_Position;
uniform vec3 Light5_Position;
uniform vec3 Light6_Position;
uniform vec3 Light7_Position;

uniform vec3 Light0_Color;
uniform vec3 Light1_Color;
uniform vec3 Light2_Color;
uniform vec3 Light3_Color;
uniform vec3 Light4_Color;
uniform vec3 Light5_Color;
uniform vec3 Light6_Color;
uniform vec3 Light7_Color;

uniform float Light0_Power;
uniform float Light1_Power;
uniform float Light2_Power;
uniform float Light3_Power;
uniform float Light4_Power;
uniform float Light5_Power;
uniform float Light6_Power;
uniform float Light7_Power;

void main()
{
	// Material properties
	vec3 MaterialDiffuseColor = diffuseColor;
	vec3 MaterialAmbientColor = ambientColor;
	vec3 MaterialSpecularColor = specularColor;

	if(terrain == 1)
	{
		MaterialAmbientColor = texture2D( myTextureSampler, UV ).rgb * worldAmbient;
		MaterialDiffuseColor = MaterialAmbientColor;
		MaterialSpecularColor = vec3(0,0,0);
	}
	else
	{

	if(textured == 1)
	{
		MaterialAmbientColor = texture2D( myTextureSampler, UV ).rgb * worldAmbient;
		MaterialDiffuseColor = diffuseColor * texture2D( myTextureSampler, UV ).rgb;
		MaterialSpecularColor = specularColor;
	}
	else
	{
		//blender wasn't exporting ambient colors, so we're using diffuse for now
		MaterialAmbientColor = MaterialDiffuseColor * worldAmbient;
	}

	}

	float distance0 = length( Light0_Position - Position_worldspace );
	float distance1 = length( Light1_Position - Position_worldspace );
	float distance2 = length( Light2_Position - Position_worldspace );
	float distance3 = length( Light3_Position - Position_worldspace );
	float distance4 = length( Light4_Position - Position_worldspace );
	float distance5 = length( Light5_Position - Position_worldspace );
	float distance6 = length( Light6_Position - Position_worldspace );
	float distance7 = length( Light7_Position - Position_worldspace );

	vec3 n = normalize( Normal_cameraspace );
	vec3 E = normalize(EyeDirection_cameraspace);

	vec3 l0 = normalize( Light0Direction_cameraspace );
	float cosTheta0 = clamp( dot( n,l0 ), 0,1 );

	vec3 l1 = normalize( Light1Direction_cameraspace );
	float cosTheta1 = clamp( dot( n,l1 ), 0,1 );

	vec3 l2 = normalize( Light2Direction_cameraspace );
	float cosTheta2 = clamp( dot( n,l2 ), 0,1 );

	vec3 l3 = normalize( Light3Direction_cameraspace );
	float cosTheta3 = clamp( dot( n,l3 ), 0,1 );

	vec3 l4 = normalize( Light4Direction_cameraspace );
	float cosTheta4 = clamp( dot( n,l4 ), 0,1 );

	vec3 l5 = normalize( Light5Direction_cameraspace );
	float cosTheta5 = clamp( dot( n,l5 ), 0,1 );

	vec3 l6 = normalize( Light6Direction_cameraspace );
	float cosTheta6 = clamp( dot( n,l6 ), 0,1 );

	vec3 l7 = normalize( Light7Direction_cameraspace );
	float cosTheta7 = clamp( dot( n,l7 ), 0,1 );

	vec3 R0 = reflect(-l0,n);
	float cosAlpha0 = clamp( dot( E,R0 ), 0,1 );

	vec3 R1 = reflect(-l1,n);
	float cosAlpha1 = clamp( dot( E,R1 ), 0,1 );

	vec3 R2 = reflect(-l2,n);
	float cosAlpha2 = clamp( dot( E,R2 ), 0,1 );

	vec3 R3 = reflect(-l3,n);
	float cosAlpha3 = clamp( dot( E,R3 ), 0,1 );

	vec3 R4 = reflect(-l4,n);
	float cosAlpha4 = clamp( dot( E,R4 ), 0,1 );

	vec3 R5 = reflect(-l5,n);
	float cosAlpha5 = clamp( dot( E,R5 ), 0,1 );

	vec3 R6 = reflect(-l6,n);
	float cosAlpha6 = clamp( dot( E,R6 ), 0,1 );

	vec3 R7 = reflect(-l7,n);
	float cosAlpha7 = clamp( dot( E,R7 ), 0,1 );

	vec3 colorPower0 = Light0_Color * Light0_Power;
	vec3 colorPower1 = Light1_Color * Light1_Power;
	vec3 colorPower2 = Light2_Color * Light2_Power;
	vec3 colorPower3 = Light3_Color * Light3_Power;
	vec3 colorPower4 = Light4_Color * Light4_Power;
	vec3 colorPower5 = Light5_Color * Light5_Power;
	vec3 colorPower6 = Light6_Color * Light6_Power;
	vec3 colorPower7 = Light7_Color * Light7_Power;

	vec3 MaterialDiffuseColor0 = colorPower0 * cosTheta0 / (distance0*distance0);
	vec3 MaterialSpecularColor0 = Light0_Color * Light0_Power * pow(cosAlpha0,5) / (distance0*distance0);

	vec3 MaterialDiffuseColor1 = colorPower1 * cosTheta1 / (distance1*distance1);
	vec3 MaterialSpecularColor1 = Light1_Color * Light1_Power * pow(cosAlpha1,5) / (distance1*distance1);

	vec3 MaterialDiffuseColor2 = colorPower2 * cosTheta2 / (distance2*distance2);
	vec3 MaterialSpecularColor2 = Light2_Color * Light2_Power * pow(cosAlpha2,5) / (distance2*distance2);

	vec3 MaterialDiffuseColor3 = colorPower3 * cosTheta3 / (distance3*distance3);
	vec3 MaterialSpecularColor3 = Light3_Color * Light3_Power * pow(cosAlpha3,5) / (distance3*distance3);

	vec3 MaterialDiffuseColor4 = colorPower4 * cosTheta4 / (distance4*distance4);
	vec3 MaterialSpecularColor4 = Light4_Color * Light4_Power * pow(cosAlpha4,5) / (distance4*distance4);

	vec3 MaterialDiffuseColor5 = colorPower5 * cosTheta5 / (distance5*distance5);
	vec3 MaterialSpecularColor5 = Light5_Color * Light5_Power * pow(cosAlpha5,5) / (distance5*distance5);

	vec3 MaterialDiffuseColor6 = colorPower6 * cosTheta6 / (distance6*distance6);
	vec3 MaterialSpecularColor6 = Light6_Color * Light6_Power * pow(cosAlpha6,5) / (distance6*distance6);

	vec3 MaterialDiffuseColor7 = colorPower7 * cosTheta7 / (distance7*distance7);
	vec3 MaterialSpecularColor7 = Light7_Color * Light7_Power * pow(cosAlpha7,5) / (distance7*distance7);
	
	color = MaterialAmbientColor;

	color += (MaterialDiffuseColor * MaterialDiffuseColor0) + (MaterialSpecularColor * MaterialSpecularColor0);
	color += (MaterialDiffuseColor * MaterialDiffuseColor1) + (MaterialSpecularColor * MaterialSpecularColor1);
	color += (MaterialDiffuseColor * MaterialDiffuseColor2) + (MaterialSpecularColor * MaterialSpecularColor2);
	color += (MaterialDiffuseColor * MaterialDiffuseColor3) + (MaterialSpecularColor * MaterialSpecularColor3);
	color += (MaterialDiffuseColor * MaterialDiffuseColor4) + (MaterialSpecularColor * MaterialSpecularColor4);
	color += (MaterialDiffuseColor * MaterialDiffuseColor5) + (MaterialSpecularColor * MaterialSpecularColor5);
	color += (MaterialDiffuseColor * MaterialDiffuseColor6) + (MaterialSpecularColor * MaterialSpecularColor6);
	color += (MaterialDiffuseColor * MaterialDiffuseColor7) + (MaterialSpecularColor * MaterialSpecularColor7);
}

My vertex shader:

#version 330 core

// Input vertex data, different for all executions of this shader.
layout(location = 0) in vec3 vertexPosition_modelspace;
layout(location = 1) in vec2 vertexUV;
layout(location = 2) in vec3 vertexNormal_modelspace;
layout(location = 3) in vec3 vertexAmbientColor;
layout(location = 4) in vec3 vertexDiffuseColor;
layout(location = 5) in vec3 vertexSpecularColor;

// Output data ; will be interpolated for each fragment.
out vec2 UV;
out vec3 Position_worldspace;
out vec3 Normal_cameraspace;
out vec3 EyeDirection_cameraspace;
out vec3 ambientColor;
out vec3 diffuseColor;
out vec3 specularColor;

out vec3 Light0Direction_cameraspace;
out vec3 Light1Direction_cameraspace;
out vec3 Light2Direction_cameraspace;
out vec3 Light3Direction_cameraspace;
out vec3 Light4Direction_cameraspace;
out vec3 Light5Direction_cameraspace;
out vec3 Light6Direction_cameraspace;
out vec3 Light7Direction_cameraspace;

// Values that stay constant for the whole mesh.
uniform mat4 MVP;
uniform mat4 V;
uniform mat4 M;

uniform vec3 Light0_Position;
uniform vec3 Light1_Position;
uniform vec3 Light2_Position;
uniform vec3 Light3_Position;
uniform vec3 Light4_Position;
uniform vec3 Light5_Position;
uniform vec3 Light6_Position;
uniform vec3 Light7_Position;

void main()
{
	// Output position of the vertex, in clip space : MVP * position
	gl_Position =  MVP * vec4(vertexPosition_modelspace,1);
	
	// Position of the vertex, in worldspace : M * position
	Position_worldspace = (M * vec4(vertexPosition_modelspace,1)).xyz;
	
	// Vector that goes from the vertex to the camera, in camera space.
	// In camera space, the camera is at the origin (0,0,0).
	vec3 vertexPosition_cameraspace = ( V * M * vec4(vertexPosition_modelspace,1)).xyz;
	EyeDirection_cameraspace = vec3(0,0,0) - vertexPosition_cameraspace;

	// Vector that goes from the vertex to the light, in camera space. M is ommited because it's identity.
	
	vec3 Light0Position_cameraspace = ( V * vec4(Light0_Position,0)).xyz;
	Light0Direction_cameraspace = Light0Position_cameraspace + EyeDirection_cameraspace;
	vec3 Light1Position_cameraspace = ( V * vec4(Light1_Position,0)).xyz;
	Light1Direction_cameraspace = Light1Position_cameraspace + EyeDirection_cameraspace;
	vec3 Light2Position_cameraspace = ( V * vec4(Light2_Position,0)).xyz;
	Light2Direction_cameraspace = Light2Position_cameraspace + EyeDirection_cameraspace;
	vec3 Light3Position_cameraspace = ( V * vec4(Light3_Position,0)).xyz;
	Light3Direction_cameraspace = Light3Position_cameraspace + EyeDirection_cameraspace;
	vec3 Light4Position_cameraspace = ( V * vec4(Light4_Position,0)).xyz;
	Light4Direction_cameraspace = Light4Position_cameraspace + EyeDirection_cameraspace;
	vec3 Light5Position_cameraspace = ( V * vec4(Light5_Position,0)).xyz;
	Light5Direction_cameraspace = Light5Position_cameraspace + EyeDirection_cameraspace;
	vec3 Light6Position_cameraspace = ( V * vec4(Light6_Position,0)).xyz;
	Light6Direction_cameraspace = Light6Position_cameraspace + EyeDirection_cameraspace;
	vec3 Light7Position_cameraspace = ( V * vec4(Light7_Position,0)).xyz;
	Light7Direction_cameraspace = Light7Position_cameraspace + EyeDirection_cameraspace;
	
	// Normal of the the vertex, in camera space
	Normal_cameraspace = ( V * M * vec4(vertexNormal_modelspace,0)).xyz; // Only correct if ModelMatrix does not scale the model ! Use its inverse transpose if not.
	
	// UV of the vertex. No special space for this one.
	UV = vertexUV;
	diffuseColor = vertexDiffuseColor;
	ambientColor = vertexAmbientColor;
	specularColor = vertexSpecularColor;
}

And some code from the program itself:

int heightMap[200][200];
GLuint terrainVAO;
GLuint terrainTexture;
GLuint terrainVertBuffer;
GLuint terrainNormalBuffer;
GLuint terrainUVBuffer;
GLuint terrainDiffBuffer;
GLuint terrainSpecBuffer;
vector<glm::vec3> terrainVerts;
vector<glm::vec2> terrainUVs;
vector<glm::vec3> terrainNormals;
vector<glm::vec3> terrainSpecs;
vector<glm::vec3> terrainDiffs;

struct tmpVec3
{
    float x,y,z;
};

tmpVec3 cross(float x1,float y1,float z1,float x2,float y2,float z2)
{
    tmpVec3 ret;
    ret.x = (y1*z2) - (z1*y2);
    ret.y = (z1*x2) - (x1*z2);
    ret.z = (x1*y2) - (y1*x2);
    return ret;
}

tmpVec3 normalize(tmpVec3 in)
{
    float length;
    length = sqrt(pow(in.x,2)+pow(in.y,2)+pow(in.z,2));
    in.x /= length;
    in.y /= length;
    in.z /= length;
    return in;
}

void recompileHeightmap()
{
    terrainVerts.empty();
    terrainUVs.empty();
    terrainNormals.empty();

    for(int x = 0; x<199; x++)
    {
        for(int z = 0; z<199; z++)
        {

            glm::vec3 temp1(-(x),heightMap[x][z],-(z));
            glm::vec3 temp2(-(x),heightMap[x][z+1],-(z+1));
            glm::vec3 temp3(-(x+1),heightMap[x+1][z],-(z));

            glm::vec3 temp4(-(x+1),heightMap[x+1][z+1],-(z+1));
            glm::vec3 temp5(-(x+1),heightMap[x+1][z],-(z));
            glm::vec3 temp6(-(x),heightMap[x][z+1],-(z+1));

            terrainVerts.push_back(temp1);
            terrainVerts.push_back(temp2);
            terrainVerts.push_back(temp3);
            terrainVerts.push_back(temp4);
            terrainVerts.push_back(temp5);
            terrainVerts.push_back(temp6);

            glm::vec3 tempDiff(1,1,1);
            glm::vec3 tempSpec(0,0,0);

            terrainDiffs.push_back(tempDiff);
            terrainDiffs.push_back(tempDiff);
            terrainDiffs.push_back(tempDiff);
            terrainDiffs.push_back(tempDiff);
            terrainDiffs.push_back(tempDiff);
            terrainDiffs.push_back(tempDiff);

            terrainSpecs.push_back(tempSpec);
            terrainSpecs.push_back(tempSpec);
            terrainSpecs.push_back(tempSpec);
            terrainSpecs.push_back(tempSpec);
            terrainSpecs.push_back(tempSpec);
            terrainSpecs.push_back(tempSpec);

            int randNum = rand() % 4;

            if(randNum == 0)
            {
                glm::vec2 uv1(0,0);
                glm::vec2 uv2(0,1);
                glm::vec2 uv3(1,0);

                glm::vec2 uv4(1,1);
                glm::vec2 uv5(1,0);
                glm::vec2 uv6(0,1);

                terrainUVs.push_back(uv1);
                terrainUVs.push_back(uv2);
                terrainUVs.push_back(uv3);
                terrainUVs.push_back(uv4);
                terrainUVs.push_back(uv5);
                terrainUVs.push_back(uv6);
            }
            else if(randNum == 1)
            {
                glm::vec2 uv1(1,1);
                glm::vec2 uv2(1,0);
                glm::vec2 uv3(0,1);

                glm::vec2 uv4(1,1);
                glm::vec2 uv5(1,0);
                glm::vec2 uv6(0,1);

                terrainUVs.push_back(uv1);
                terrainUVs.push_back(uv2);
                terrainUVs.push_back(uv3);
                terrainUVs.push_back(uv4);
                terrainUVs.push_back(uv5);
                terrainUVs.push_back(uv6);
            }
            else if(randNum == 2)
            {
                glm::vec2 uv1(0,0);
                glm::vec2 uv2(0,1);
                glm::vec2 uv3(1,0);

                glm::vec2 uv4(1,0);
                glm::vec2 uv5(0,1);
                glm::vec2 uv6(1,1);

                terrainUVs.push_back(uv1);
                terrainUVs.push_back(uv2);
                terrainUVs.push_back(uv3);
                terrainUVs.push_back(uv4);
                terrainUVs.push_back(uv5);
                terrainUVs.push_back(uv6);
            }
            else
            {
                glm::vec2 uv1(1,1);
                glm::vec2 uv2(1,0);
                glm::vec2 uv3(0,1);

                glm::vec2 uv4(1,1);
                glm::vec2 uv5(1,0);
                glm::vec2 uv6(0,1);

                terrainUVs.push_back(uv1);
                terrainUVs.push_back(uv2);
                terrainUVs.push_back(uv3);
                terrainUVs.push_back(uv4);
                terrainUVs.push_back(uv5);
                terrainUVs.push_back(uv6);
            }
        }
    }

    for(int i = 0; i<terrainVerts.size(); i+=3)
    {
        glm::vec3 first = terrainVerts[i];
        glm::vec3 second = terrainVerts[i+1];
        glm::vec3 third = terrainVerts[i+2];

        float v1x = second.x - first.x;
        float v1y = second.y - first.y;
        float v1z = second.z - first.z;
        float v2x = third.x - first.x;
        float v2y = third.y - first.y;
        float v2z = third.z - first.z;

        tmpVec3 ret = normalize(cross(v1x,v1y,v1z,v2x,v2y,v2z));

        glm::vec3 normal(-ret.x,ret.y,-ret.z);

        terrainNormals.push_back(normal);
        terrainNormals.push_back(normal);
        terrainNormals.push_back(normal);
    }

    glGenVertexArrays(1,&terrainVAO);
    glBindVertexArray(terrainVAO);

    glBindTexture(GL_TEXTURE_2D, terrainTexture);

    glGenBuffers(1, &terrainVertBuffer);
    glEnableVertexAttribArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, terrainVertBuffer);
    glBufferData(GL_ARRAY_BUFFER, terrainVerts.size() * sizeof(glm::vec3), &terrainVerts[0], GL_STATIC_DRAW);
    glVertexAttribPointer(
            0,                  // attribute
            3,                  // size
            GL_FLOAT,           // type
            GL_FALSE,           // normalized?
            0,                  // stride
            (void*)0            // array buffer offset
    );

    glGenBuffers(1, &terrainUVBuffer);
    glEnableVertexAttribArray(1);
    glBindBuffer(GL_ARRAY_BUFFER, terrainUVBuffer);
    glBufferData(GL_ARRAY_BUFFER, terrainUVs.size() * sizeof(glm::vec2), &terrainUVs[0], GL_STATIC_DRAW);
    glVertexAttribPointer(
            1,                  // attribute
            2,                  // size
            GL_FLOAT,           // type
            GL_FALSE,           // normalized?
            0,                  // stride
            (void*)0            // array buffer offset
    );

    glGenBuffers(1, &terrainNormalBuffer);
    glEnableVertexAttribArray(2);
    glBindBuffer(GL_ARRAY_BUFFER, terrainNormalBuffer);
    glBufferData(GL_ARRAY_BUFFER, terrainNormals.size() * sizeof(glm::vec3), &terrainNormals[0], GL_STATIC_DRAW);
    glVertexAttribPointer(
            2,                                // attribute
            3,                                // size
            GL_FLOAT,                         // type
            GL_FALSE,                         // normalized?
            0,                                // stride
            (void*)0                          // array buffer offset
    );

        glGenBuffers(1, &terrainDiffBuffer);
        glEnableVertexAttribArray(4);
        glBindBuffer(GL_ARRAY_BUFFER, terrainDiffBuffer);
        glBufferData(GL_ARRAY_BUFFER, terrainDiffs.size() * sizeof(glm::vec3), &terrainDiffs[0], GL_STATIC_DRAW);
        glVertexAttribPointer(
                4,                                // attribute
                3,                                // size
                GL_FLOAT,                         // type
                GL_FALSE,                         // normalized?
                0,                                // stride
                (void*)0                          // array buffer offset
        );

        glGenBuffers(1, &terrainSpecBuffer);
        glEnableVertexAttribArray(5);
        glBindBuffer(GL_ARRAY_BUFFER, terrainSpecBuffer);
        glBufferData(GL_ARRAY_BUFFER, terrainSpecs.size() * sizeof(glm::vec3), &terrainSpecs[0], GL_STATIC_DRAW);
        glVertexAttribPointer(
                5,                                // attribute
                3,                                // size
                GL_FLOAT,                         // type
                GL_FALSE,                         // normalized?
                0,                                // stride
                (void*)0                          // array buffer offset
        );
}

Called each frame:

        glBindTexture(GL_TEXTURE_2D, terrainTexture);
        glBindVertexArray(terrainVAO);
        glDrawArrays(GL_TRIANGLES, 0, terrainVerts.size() );

I may not have provided enough information, however if there are any improvements at all that anyone can suggest, I'd love to hear them before I start devloping anything more advanced.
 

 


Edited by Syerjchep, 07 September 2013 - 05:04 PM.


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#2 cozzie   Members   -  Reputation: 1758

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Posted 08 September 2013 - 08:56 AM

It somehow looks like your point light on the corner where your terrain goes up, moves with the camera. But that might be just visual / misleading.

Another thing you could test is moving that specific light source to eather the steaper or the flat mesh, and see what the result is. If is is correct, then you have to look somewhere where the lighting affects more then one (big) mesh, in this case the terrain.




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