[Mesa-users] Blank screen with Mesa_offscreen render 11.1.2

[vikramnrao]

Hi Brian,

I managed to get it work with Mesa 7.5.1. Since there was an urgent
requirement for off-screen rendering I am using this.
However I have tried by clearing the screen to blue color which is working
fine.The problem should be else where. Will look into it and update.


Thanks &  Regards,
Vikram

On Sun, Apr 3, 2016 at 1:56 AM, Brian Paul <brianp at vmware.com> wrote:

> I guess I'd start by trimming down the program, or writing a new test
> case, that does something extremely simple, like clearing the surface to
> non-black and see if that works.
>
> -Brian
>
> On 03/25/2016 02:16 AM, vikramnrao wrote:
>
>> 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
>> <mailto: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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