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D3DHAL_DP2TRIANGLEFAN_IMM structure

One D3DHAL_DP2TRIANGLEFAN_IMM structure is parsed from the command buffer by the D3dDrawPrimitives2 callback when the D3DHAL_DP2COMMAND structure's bCommand member is set to D3DDP2OP_TRIANGLEFAN_IMM, and is used to render a triangle fan.

Syntax


typedef struct _D3DHAL_DP2TRIANGLEFAN_IMM {
  DWORD dwEdgeFlags;
} D3DHAL_DP2TRIANGLEFAN_IMM, *LPD3DHAL_DP2TRIANGLEFAN_IMM;

Members

dwEdgeFlags

Specifies a bitmask that identifies which of the fan's outside edges should be rendered when the fill mode is D3DFILL_WIREFRAME. A set bit indicates that its corresponding edge should be rendered. For more information about this bitmask, see the Remarks section.

Remarks

One D3DHAL_DP2TRIANGLEFAN_IMM structure immediately follows the D3DHAL_DP2COMMAND structure in the command buffer. The triangle fan's vertex data is DWORD-aligned immediately following the D3DHAL_DP2TRIANGLEFAN_IMM structure in the command buffer.

D3dDrawPrimitives2 should process a total of wPrimitiveCount+2 vertices from the command buffer, three vertices per triangle, rendering wPrimitiveCount triangles. The sequence of triangles rendered is (V[1], V[2], V[0]), (V[2], V[3], V[0]), (V[3], V[4], V[0]), ..., (V[wPrimitiveCount], V[wPrimitiveCount] + 1], V[0]). The value of wPrimitiveCount is specified in the D3DHAL_DP2COMMAND structure.

The driver must check the edge flag for each of the fan's outside edges when the fill mode is D3DFILL_WIREFRAME. Starting from the least significant bit of dwEdgeFlags, bit 0 applies to the V[0]-V[1] edge, bit 1 applies to the V[1]-V[2] edge, ..., bit wPrimitiveCount applies to the V[wPrimitiveCount]-V[[wPrimitiveCount]+1] edge, and bit (wPrimitiveCount + 1) applies to the V[[wPrimitiveCount]+1]-V[0] edge.

The following figure shows a portion of a sample command buffer containing a D3DDP2OP_TRIANGLEFAN_IMM command, a D3DHAL_DP2TRIANGLEFAN_IMM structure, and the vertex data. The driver should process the five vertices from the command buffer, rendering a fan with three triangles defined by (v[1], v[2], v[0]), (v[2], v[3], v[0]), (v[3], v[4], v[0]).

Figure showing a command buffer with a D3DDP2OP_TRIANGLEFAN_IMM command, a D3DHAL_DP2TRIANGLEFAN_IMM structure, and the vertex data

Requirements

Header

D3dhal.h (include D3dhal.h)

See also

D3DDP2OP_TRIANGLEFAN_IMM
D3dDrawPrimitives2
D3DHAL_DP2COMMAND

 

 

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