diff options
| -rw-r--r-- | src/mesa/swrast/s_depth.c | 41 |
1 files changed, 27 insertions, 14 deletions
diff --git a/src/mesa/swrast/s_depth.c b/src/mesa/swrast/s_depth.c index 0b6bb7e3ec9..ac5dae2148b 100644 --- a/src/mesa/swrast/s_depth.c +++ b/src/mesa/swrast/s_depth.c @@ -497,17 +497,24 @@ depth_test_span32( GLcontext *ctx, GLuint n, return passed; } -/* Apply ARB_depth_clamp to span of fragments. */ + + +/** + * Clamp fragment Z values to the depth near/far range (glDepthRange()). + * This is used when GL_ARB_depth_clamp/GL_DEPTH_CLAMP is turned on. + * In that case, vertexes are not clipped against the near/far planes + * so rasterization will produce fragment Z values outside the usual + * [0,1] range. + */ void _swrast_depth_clamp_span( GLcontext *ctx, SWspan *span ) { struct gl_framebuffer *fb = ctx->DrawBuffer; - struct gl_renderbuffer *rb = fb->_DepthBuffer; const GLuint count = span->end; - GLuint *zValues = span->array->z; - GLuint min, max; + GLint *zValues = (GLint *) span->array->z; /* sign change */ + GLint min, max; GLfloat min_f, max_f; - int i; + GLuint i; if (ctx->Viewport.Near < ctx->Viewport.Far) { min_f = ctx->Viewport.Near; @@ -517,15 +524,21 @@ _swrast_depth_clamp_span( GLcontext *ctx, SWspan *span ) max_f = ctx->Viewport.Near; } - if (rb->DataType == GL_UNSIGNED_SHORT) { - CLAMPED_FLOAT_TO_USHORT(min, min_f); - CLAMPED_FLOAT_TO_USHORT(max, max_f); - } else { - assert(rb->DataType == GL_UNSIGNED_INT); - min = FLOAT_TO_UINT(min_f); - max = FLOAT_TO_UINT(max_f); - } - + /* Convert floating point values in [0,1] to device Z coordinates in + * [0, DepthMax]. + * ex: If the the Z buffer has 24 bits, DepthMax = 0xffffff. + * + * XXX this all falls apart if we have 31 or more bits of Z because + * the triangle rasterization code produces unsigned Z values. Negative + * vertex Z values come out as large fragment Z uints. + */ + min = (GLint) (min_f * fb->_DepthMaxF); + max = (GLint) (max_f * fb->_DepthMaxF); + if (max < 0) + max = 0x7fffffff; /* catch over flow for 30-bit z */ + + /* Note that we do the comparisons here using signed integers. + */ for (i = 0; i < count; i++) { if (zValues[i] < min) zValues[i] = min; |