Need Help for 8bit Surface under OpenGl

SDL Development
1

Hi i figured out of how to use 8bit surface in opengl but i need some help
to apply the pallet.

the loading of the texture is like this( we load a 8bit pcx file)

SDL_RWops *rwop = SDL_RWFromMem(tex->byImage, tex->nLength );
SDL_Surface *tmp = IMG_LoadTyped_RW(rwop,1,“PCX”);

int w = tex->tex_width;
int h = tex->tex_heigth;

for(int x = 0;x< tmp->w;x++)
{
    for(int y = 0;y< tmp->h;y++)
    {
        //copy  the pixel data to an array wich is compatible has a

compatible width and heigth for opengl
tmpImage[x + yw] = pix[x + ypitch] ; // = u8[2048*2048];

    }

}

SDL_FreeSurface(tmp);

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textures[nCurrTex]);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST); // Set

Texture Max Filter
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);

//create a 1byte texture which is black and white

glTexImage2D(GL_TEXTURE_2D, 0, 1, w, h, 0, GL_RED, GL_UNSIGNED_BYTE,
tmpImage);

// now lets create the pallet texture
nCurrTex++;

glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, textures[nCurrTex]);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST); // Set

Texture Max Filter
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);

for(int i=0;i<256;i++)
{

   colorTable[i] = ((pUsedPal[i].r) << 16) | ((pUsedPal[i].g) << 8) |

(pUsedPal[i].b);
}

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 256, 1, 0, GL_RGB,
GL_UNSIGNED_BYTE,colorTable);

glUniform1i(glGetUniformLocation(FragmentShader, "Texture0"), 0);
glUniform1i(glGetUniformLocation(FragmentShader, "Texture1"), 1);

to applay the pallet to it my idee is to use a 256 x 1 texture in an pxiel
shader

here the fragment shader

uniform sampler2D Texture0; // Texture
uniform sampler2D Texture1; // Pallet

void main()
{

vec4 color =  texture2D(Texture0, gl_TexCoord[0].st);


//this should find the right color in the Pallet
float index  =  color.r * 256.0;
vec4 col   =  texture2D(Texture1, vec2(index,0) );


if(color.r == 0.0 )
discard;
else
   gl_FragColor = color;

}

2

Hi i figured out of how to use 8bit surface in opengl but i need some
help to apply the pallet.

the loading of the texture is like this( we load a 8bit pcx file)

SDL_RWops *rwop = SDL_RWFromMem(tex->byImage, tex->nLength );
SDL_Surface *tmp = IMG_LoadTyped_RW(rwop,1,“PCX”);

int w = tex->tex_width;
int h = tex->tex_heigth;

for(int x = 0;x< tmp->w;x++)
{
    for(int y = 0;y< tmp->h;y++)
    {
        //copy  the pixel data to an array wich is compatible has

a compatible width and heigth for opengl
tmpImage[x + yw] = pix[x + ypitch] ; // =
u8[2048*2048];

    }

}

SDL_FreeSurface(tmp);

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textures[nCurrTex]);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);

// Set Texture Max Filter
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);

//create a 1byte texture which is black and white

glTexImage2D(GL_TEXTURE_2D, 0, 1, w, h, 0, GL_RED,
GL_UNSIGNED_BYTE, tmpImage);

// now lets create the pallet texture
nCurrTex++;

glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, textures[nCurrTex]);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);

// Set Texture Max Filter
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);

for(int i=0;i<256;i++)
{

   colorTable[i] = ((pUsedPal[i].r) << 16) | ((pUsedPal[i].g) <<

  1. | (pUsedPal[i].b);
    }

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 256, 1, 0, GL_RGB,
    GL_UNSIGNED_BYTE,colorTable);

    glUniform1i(glGetUniformLocation(FragmentShader, “Texture0”), 0);
    glUniform1i(glGetUniformLocation(FragmentShader, “Texture1”), 1);

to applay the pallet to it my idee is to use a 256 x 1 texture in an
pxiel shader

Use 256 texel wide 1D texture instead.

here the fragment shader

uniform sampler2D Texture0; // Texture
uniform sampler2D Texture1; // Pallet

void main()
{

vec4 color =  texture2D(Texture0, gl_TexCoord[0].st);


//this should find the right color in the Pallet
float index  =  color.r * 256.0;
vec4 col   =  texture2D(Texture1, vec2(index,0) );

This is wrong, and there is no point doing this lookup if the pixel is
to be discarded. See below for the correct lookup.

if(color.r == 0.0 )
discard;
else
   gl_FragColor = color;

// 1D texture version
gl_FragColor = texture1D( Texture1, color.r );
// 2D texture version
gl_FragColor = texture2D( Texture1, vec2( color.r, 0.0 );On Friday 14 July 2006 17:22, Vardar Sahin wrote:

}