[Mesa-users] Blank screen with Mesa_offscreen render 11.1.2

[vikramnrao]

Hi Brian,

I added glFlush and glFinish still no luck with that.
Am I doing something wrong in the shader code ?
The same code works fine with the openGL libraries using freeglut and glew.


Thanks & Regards,
Vikram

On Thu, Mar 24, 2016 at 7:15 PM, Brian Paul <brianp at vmware.com> wrote:

> On 03/24/2016 12:45 AM, vikramnrao wrote:
>
>> Hi,
>>
>> Its been quite sometime that I am looking into Off screen rendering
>> using Mesa 11.1.2. :)
>>
>> I was able to render the textured model using Mesa 7.5.1 but somehow I
>> couldn't manage lighting the scene there.
>>
>> However I want my code to run using Mesa 11.1.2.
>> I am not able to see anything in the off-screen rendered targa image.
>> It just appears blank.
>>
>> What is wrong in the following code ?
>>
>> [...]
>
>
>
>>
>> glGetError();
>> // Draw the triangle !
>> glDrawArrays(GL_TRIANGLES, 0, indexed_vertex_data.size());
>>
>
> Try putting a glFlush() or glFinish() call here.
>
> -Brian
>
>
>
>
>> SaveScreenGrab("mesa_snapshot.tga");
>>
>>
>> glDisableVertexAttribArray(vertexPosition_modelspaceID);
>>
>> // Cleanup VBO
>> glDeleteBuffers(1, &vertexbuffer);
>> glDeleteBuffers(1, &normalbuffer);
>> glDeleteBuffers(1, &uvbuffer);
>> glDeleteTextures(1, &diffuseMap);
>> glDeleteProgram(programID);
>>
>> }
>>
>> *************************
>> Shader code
>> *************************
>> --------------------
>> vertex shader:
>> ---------------------
>>
>>   attribute vec3 vertexPosition_modelspace;
>>   attribute vec2 vertexUV;
>>   attribute vec3 normalv;
>>
>>   varying vec2 TexCoords;
>>   varying vec3 normalf;
>>   varying vec3 FragPos;
>>
>>   uniform mat4 MVP;
>>   uniform mat4 Model;
>>
>>
>>   void main() {
>>
>> gl_Position = MVP * vec4(vertexPosition_modelspace,1);
>>      FragPos = vec3(Model * vec4(vertexPosition_modelspace,1));
>>      normalf = vec3(Model * vec4(normalv,1));
>>      TexCoords = vertexUV;
>>
>>   }
>>
>>
>> ------------------------
>> Fragment shader:
>> -------------------------
>>   #version 120
>>
>> struct Material{
>>      vec4 ambient;
>>      vec4 diffuse;
>>      vec4 specular;
>>      float shininess;
>> };
>>
>> struct DirLight {
>>      vec3 direction;
>>      vec3 ambient;
>>      vec3 diffuse;
>>      vec3 specular;
>> };
>>
>>
>> in vec3 FragPos;
>> in vec3 normalf;
>> in vec2 TexCoords;
>> in vec3 vertexColor;
>> vec4 texel0;
>>
>> uniform sampler2D MeshTexture;
>> uniform DirLight dirLight;
>> out vec4 ResultFragColor;
>> uniform vec3 viewPos;
>> uniform Material material;
>> uniform float matAlpha;
>>
>> //Function prototype
>> vec4 SurfaceColor (in Material mat, in vec4 texel);
>>
>> void main()
>> {
>>
>>       texel0 = texture2D(MeshTexture, TexCoords);
>>
>>      vec3 norm = normalize(normalf);
>> vec3 viewDir = normalize(viewPos - FragPos);
>> vec3 lightDir = normalize(-dirLight.direction);
>>
>>      // Diffuse shading
>>      float diff = max(dot(norm, lightDir), 0.0);
>>
>>      // Specular shading
>>      vec3 reflectDir = reflect(-lightDir, norm);
>>      float spec = pow(max(dot(viewDir, reflectDir), 0.0),
>> material.shininess);
>>
>> vec4 surfaceColorValue ;
>> surfaceColorValue = mix(material.diffuse, texel0, texel0.a);
>> surfaceColorValue.a =  min(matAlpha*( 1 + texel0.a) , 1);
>>
>> vec4 ambient = vec4(dirLight.ambient, 1)  * surfaceColorValue ;
>> vec4 diffuse = vec4(dirLight.diffuse, 1) * diff * surfaceColorValue ;
>> vec4 specular = vec4(dirLight.specular, 1)  * spec  * material.specular ;
>>
>> vec4 result = ambient + diffuse + specular ;
>>
>> ResultFragColor = result;
>>
>> }
>>
>> vec4 SurfaceColor (in Material mat, in vec4 texel)
>> {
>>   vec4 SurfColor;
>>
>>   SurfColor = mix(mat.diffuse, texel, texel.a);
>>   SurfColor.a =  min(matAlpha*( 1 + texel.a) , 1);
>>   return SurfColor;
>> }
>>
>> }
>>
>>
>>
>>
>> Thanks & Regards,
>> Vikram
>>
>
>
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