c++ - OpenGL 3.3 texture mapping triangle -

i have had little luck texturing triangle in opengl 3.3 (core) on last few days. can render vertices , colors, texturing seems problematic. current task/goal vertices , texture coordinates (no colors).

since create test texture hand, should show 16x16 white/red checkered triangle.

strange behavior: if use gl_clamp_to_edge, it's white. if use gl_repeat, comes out pink (white + red)...

vertex shader:

#version 330 layout (location = 0) in vec3 vertpos; layout (location = 1) in vec2 texcoord; out vec2 tex; uniform mat4 viewmatrix, projmatrix; void main() {   gl_position = projmatrix * viewmatrix * vec4(vertpos,1.0);   tex = texcoord; }; 

fragment shader:

#version 330 out vec4 color; in vec2 tex; uniform sampler2d texsampler; void main() {   color = texture(texsampler, tex); }; 

state initialization code (these in order shown):

  glpixelstorei(gl_unpack_alignment,1);   //glpixelstorei(gl_pack_alignment,1);    glfrontface(gl_cw);  // clockwise oriented polys front faces   glcullface(gl_back); // cull out inner polygons... set culling property appropriately    gllinewidth(1.0f); // wireframe    glblendfunc(gl_src_alpha,gl_one_minus_src_alpha); // color 1.0f opaque, 0.0f transparent    gldepthfunc(gl_lequal);   gldepthrange(0,1); // default    gldisable(gl_cull_face);    glclearcolor(0.0f,0.0f,0.0f,1.0f); // set clear color black    glpolygonmode(gl_front_and_back,gl_fill); // filled polys 

texture initialization:

  glgentextures(1,&texid1);   glbindtexture (gl_texture_2d, texid1);    gltexparameteri(gl_texture_2d,gl_texture_mag_filter,gl_linear);   gltexparameteri(gl_texture_2d,gl_texture_min_filter,gl_linear);    gltexparameteri(gl_texture_2d, gl_texture_base_level, 0);   gltexparameteri(gl_texture_2d, gl_texture_max_level, 0);    gltexparameteri(gl_texture_2d, gl_texture_wrap_s, gl_clamp_to_edge);   gltexparameteri(gl_texture_2d, gl_texture_wrap_t, gl_clamp_to_edge);      uint32 buf[16*16];     uint32 x;     (x=0;x<16*16;) {       buf[x++] = 0xffffffff;       buf[x++] = 0xffff0000;     }      glteximage2d (gl_texture_2d, 0, gl_rgba8 , 16, 16, 0, gl_bgra, gl_unsigned_byte, (void*)buf);    glbindtexture (gl_texture_2d, 0); 

shader initialization:

  shader1 = new_gl_shader_program(vert_src,frag_src);   if (shader1) {     if (link_gl_shader_program(shader1)) {        projmatrixloc = glgetuniformlocation(shader1, "projmatrix");       viewmatrixloc = glgetuniformlocation(shader1, "viewmatrix");        sampler2dloc = glgetuniformlocation(shader1, "texsampler");        glbindfragdatalocation( shader1, 0, "color" ); // added.      }     else {       print("link error: %s\n",get_gl_shader_msg());       delete_gl_shader_program(shader1);       shader1 = 0;     }   }   else     print("compile/misc error: %s\n",get_gl_shader_msg());    if (!shader1)     return; 

buffer data initialization:

typedef struct mesh_vert_3d {   float x,y,z;   float u,v; }mesh_vert_3d;  mesh_vert_3d meshbuf[3]; // total of 15 floats      meshbuf[0].x = 0.0f;     meshbuf[0].y = 0.0f;     meshbuf[0].z = 0.0f;      meshbuf[1].x = 1.0f;     meshbuf[1].y = 0.0f;     meshbuf[1].z = 0.0f;      meshbuf[2].x = 1.0f;     meshbuf[2].y = 0.0f;     meshbuf[2].z = 1.0f;      meshbuf[0].u = 0.0f;     meshbuf[0].v = 1.0f;     meshbuf[1].u = 1.0f;     meshbuf[1].v = 1.0f;     meshbuf[2].u = 1.0f;     meshbuf[2].v = 0.0f;      glgenbuffers(1, &vboid);     glbindbuffer(gl_array_buffer, vboid);     glbufferdata(gl_array_buffer, sizeof(meshbuf), meshbuf, gl_static_draw);     glbindbuffer(gl_array_buffer, 0);      glgenvertexarrays(1, &vaohandle);     glbindvertexarray(vaohandle);      glbindbuffer(gl_array_buffer, vboid);     glvertexattribpointer(0, 3, gl_float, gl_false, sizeof(float)*5, null);     glenablevertexattribarray(0);     glvertexattribpointer(1, 2, gl_float, gl_false,sizeof(float)*5, (void*)(sizeof(float)*3));     glenablevertexattribarray(1);      glbindvertexarray(0);     gldisablevertexattribarray(0);     gldisablevertexattribarray(1);     glbindbuffer(gl_array_buffer, 0); 

render:

  gls_begin_3d(&glscene);   use_gl_shader_program(shader1);    gluniformmatrix4fv(projmatrixloc,  1, gl_false, gls_get_projection_matrix());   gluniformmatrix4fv(viewmatrixloc,  1, gl_false, gls_get_modelview_matrix());    glactivetexture(gl_texture0);   glbindtexture (gl_texture_2d, texid1);   gluniform1i(sampler2dloc, 0);    glbindvertexarray(vaohandle);    gldrawarrays(gl_triangles, 0, 3 );    glbindtexture (gl_texture_2d, 0);    use_gl_shader_program(0);   gls_end_3d(&glscene); 

issue 1:

you should bind fragment shader output variable color fragment data location:

glbindfragdatalocation( shader1, 0, "color" ); 

otherwise opengl not know results of shader program located.

issue 2:

you create second buffer object texture coordinates: glgenbuffers(1, &tboid); however, should put single vbo.

issue 3:

you pass null glvertexattribpointer(1, 2, gl_float, gl_false,sizeof(float)*5, null); however, beginning of texture coordinates not 0. sizeof(float)*3.

issue 4:

in vertex shader, have out vec2 texcoordout;. however, in fragment shader, use in vec2 tex;. names should match.